chore(release): 4.67.3 [skip ci]

## [4.67.3](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.67.2...v4.67.3) (2025-10-23)

### Bug Fixes

* **complement-race:** resolve infinite render loop in useTrackManagement ([8b4dacd](8b4dacdc98))

CHANGELOG.md

@@ -1,3 +1,320 @@
+## [4.67.3](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.67.2...v4.67.3) (2025-10-23)
+
+
+### Bug Fixes
+
+* **complement-race:** resolve infinite render loop in useTrackManagement ([8b4dacd](https://github.com/antialias/soroban-abacus-flashcards/commit/8b4dacdc98cc8cb2a503b31698430ad7ffb6ef8e))
+
+## [4.67.2](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.67.1...v4.67.2) (2025-10-23)
+
+
+### Performance Improvements
+
+* **complement-race:** increase train position update frequency to 60fps ([fffaf1d](https://github.com/antialias/soroban-abacus-flashcards/commit/fffaf1df1d4d55c811bf634c957691e3564470d6))
+
+## [4.67.1](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.67.0...v4.67.1) (2025-10-22)
+
+
+### Bug Fixes
+
+* **complement-race:** fix react-spring interpolation TypeScript errors ([0add9e4](https://github.com/antialias/soroban-abacus-flashcards/commit/0add9e4ef1d69e4e92ffe279cce09c68efa43714))
+
+## [4.67.0](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.66.2...v4.67.0) (2025-10-22)
+
+
+### Features
+
+* **complement-race:** add react-spring animations to ghost trains for smooth movement ([eb3700a](https://github.com/antialias/soroban-abacus-flashcards/commit/eb3700a57d035a142c64b60d5d1b21181d21b69f))
+
+## [4.66.2](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.66.1...v4.66.2) (2025-10-22)
+
+
+### Bug Fixes
+
+* **complement-race:** fix ghost train position update lag and reload position reset ([ad78a65](https://github.com/antialias/soroban-abacus-flashcards/commit/ad78a65ed7f63509602e79246e3761653ea39a15))
+
+## [4.66.1](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.66.0...v4.66.1) (2025-10-22)
+
+
+### Bug Fixes
+
+* **complement-race:** ensure continuous position broadcasting during train movement ([df60824](https://github.com/antialias/soroban-abacus-flashcards/commit/df60824f37f52e77e69d32c26926a24e1af88e66))
+
+## [4.66.0](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.65.1...v4.66.0) (2025-10-22)
+
+
+### Features
+
+* **complement-race:** implement per-car adaptive opacity for ghost trains ([9b1d47d](https://github.com/antialias/soroban-abacus-flashcards/commit/9b1d47d4c7bdaf44f3921ff99971dfb3b65442bd))
+
+## [4.65.1](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.65.0...v4.65.1) (2025-10-22)
+
+
+### Bug Fixes
+
+* **complement-race:** use sendMove with correct parameters for position updates ([06cd94b](https://github.com/antialias/soroban-abacus-flashcards/commit/06cd94b24cdd9dbd36fb5800c9ba7be194f7eed0))
+
+## [4.65.0](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.64.2...v4.65.0) (2025-10-22)
+
+
+### Features
+
+* **complement-race:** implement position broadcasting for ghost trains ([c5fba5b](https://github.com/antialias/soroban-abacus-flashcards/commit/c5fba5b7dd0f36fd3bbe596409e01b0d3dbd4fbe))
+
+## [4.64.2](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.64.1...v4.64.2) (2025-10-22)
+
+
+### Bug Fixes
+
+* **complement-race:** use individual player positions for ghost trains ([00dc4b1](https://github.com/antialias/soroban-abacus-flashcards/commit/00dc4b1d06a4e1763deb16333a298145cafd9187))
+
+## [4.64.1](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.64.0...v4.64.1) (2025-10-22)
+
+
+### Bug Fixes
+
+* **complement-race:** use local player instead of first player for train display ([915d8a5](https://github.com/antialias/soroban-abacus-flashcards/commit/915d8a5343e70a30c7a82bed645e6628fcc08a86))
+
+## [4.64.0](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.63.11...v4.64.0) (2025-10-22)
+
+
+### Features
+
+* **complement-race:** add ghost trains for multiplayer visibility ([7668cc9](https://github.com/antialias/soroban-abacus-flashcards/commit/7668cc9b113b3eae2acb1b852b0ad48c979e6604))
+
+## [4.63.11](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.63.10...v4.63.11) (2025-10-22)
+
+
+### Bug Fixes
+
+* **complement-race:** actually filter by isActive instead of just id ([ef4ca57](https://github.com/antialias/soroban-abacus-flashcards/commit/ef4ca57a6c3f35d1bddc6a70952f478058fbc6b5))
+
+## [4.63.10](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.63.9...v4.63.10) (2025-10-22)
+
+
+### Bug Fixes
+
+* **complement-race:** show only first active player's passengers on train ([2bfd5d2](https://github.com/antialias/soroban-abacus-flashcards/commit/2bfd5d2bda7f7d2d83c69f75600ab461fde15d92))
+
+## [4.63.9](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.63.8...v4.63.9) (2025-10-21)
+
+
+### Bug Fixes
+
+* **homepage:** use app-wide abacus config in interactive flashcards ([cf1be2d](https://github.com/antialias/soroban-abacus-flashcards/commit/cf1be2d1730543bd30836a87d9cbdfd2cf48360e))
+
+## [4.63.8](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.63.7...v4.63.8) (2025-10-21)
+
+
+### Bug Fixes
+
+* **mobile:** restore abacus visibility in "Your Journey" section ([c96036d](https://github.com/antialias/soroban-abacus-flashcards/commit/c96036d86b6de2e25f7ecd3d00dd36221badc3b1))
+
+## [4.63.7](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.63.6...v4.63.7) (2025-10-21)
+
+
+### Bug Fixes
+
+* **mobile:** reduce height of Your Journey section on mobile ([8944035](https://github.com/antialias/soroban-abacus-flashcards/commit/89440355bf494e54072d2d1a1f228c33ec43d52d))
+
+## [4.63.6](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.63.5...v4.63.6) (2025-10-21)
+
+
+### Bug Fixes
+
+* **mobile:** optimize Your Journey section for iPhone displays ([9167fb4](https://github.com/antialias/soroban-abacus-flashcards/commit/9167fb40d68b7bdbe310b647083586434ceb6043))
+
+## [4.63.5](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.63.4...v4.63.5) (2025-10-21)
+
+
+### Bug Fixes
+
+* **flashcards:** store grab offset in local coordinates to prevent jump ([39d93a9](https://github.com/antialias/soroban-abacus-flashcards/commit/39d93a9e9f48a7d1ce10763cad62a600851a41d5))
+
+## [4.63.4](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.63.3...v4.63.4) (2025-10-21)
+
+
+### Bug Fixes
+
+* **flashcards:** keep grab point under cursor with proper coordinate conversion ([1869216](https://github.com/antialias/soroban-abacus-flashcards/commit/1869216d2fda77303c0b79d4f613c6dcdaf5324b))
+
+## [4.63.3](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.63.2...v4.63.3) (2025-10-21)
+
+
+### Bug Fixes
+
+* **flashcards:** revert to simple delta positioning to prevent card jumping ([d018b69](https://github.com/antialias/soroban-abacus-flashcards/commit/d018b699c46aea90e9cdc3309e797ff2d7447ecf))
+
+## [4.63.2](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.63.1...v4.63.2) (2025-10-21)
+
+
+### Bug Fixes
+
+* **flashcards:** correct pivot point to rotate around card center ([50fc3fd](https://github.com/antialias/soroban-abacus-flashcards/commit/50fc3fdf7f2c9b7412f6d7d890f5e0d52cb86a9b))
+
+## [4.63.1](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.63.0...v4.63.1) (2025-10-21)
+
+
+### Bug Fixes
+
+* **flashcards:** increase rotation sensitivity 10x for visible grab point physics ([c0fa926](https://github.com/antialias/soroban-abacus-flashcards/commit/c0fa926d16d02c1bfe880b7f0056a760e8461b3b))
+
+## [4.63.0](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.62.1...v4.63.0) (2025-10-21)
+
+
+### Features
+
+* **flashcards:** add grab point physics for realistic rotation ([bf37eb1](https://github.com/antialias/soroban-abacus-flashcards/commit/bf37eb1928de8d07673234e2faa1fa6268c45686))
+
+## [4.62.1](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.62.0...v4.62.1) (2025-10-21)
+
+
+### Bug Fixes
+
+* **flashcards:** improve shadow speed logging with separate throttling ([0f51366](https://github.com/antialias/soroban-abacus-flashcards/commit/0f51366fd56540e691df4931b6350c03043484f1))
+
+## [4.62.0](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.61.3...v4.62.0) (2025-10-21)
+
+
+### Features
+
+* **flashcards:** add dynamic shadow based on drag speed ([92148a4](https://github.com/antialias/soroban-abacus-flashcards/commit/92148a4cf87e828ba2e5ec1740fb51d9667c1d73))
+
+## [4.61.3](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.61.2...v4.61.3) (2025-10-21)
+
+
+### Code Refactoring
+
+* **flashcards:** completely rewrite drag-drop with simple approach ([5f0ad14](https://github.com/antialias/soroban-abacus-flashcards/commit/5f0ad14133340d073e861f5721cb48e1abab03ff))
+
+## [4.61.2](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.61.1...v4.61.2) (2025-10-21)
+
+
+### Bug Fixes
+
+* **flashcards:** use explicit per-property configs to fix decay physics ([f32480a](https://github.com/antialias/soroban-abacus-flashcards/commit/f32480a0f9153285341e5a28078840abc0590873))
+
+## [4.61.1](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.61.0...v4.61.1) (2025-10-21)
+
+
+### Bug Fixes
+
+* **flashcards:** fix position snap-back by using api.set before decay ([30e16c8](https://github.com/antialias/soroban-abacus-flashcards/commit/30e16c8e5ac3bb25f2d54cf715dc6fb45adc4fcc))
+
+## [4.61.0](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.60.0...v4.61.0) (2025-10-21)
+
+
+### Features
+
+* **flashcards:** enable unbounded drag and position persistence ([ad1ad69](https://github.com/antialias/soroban-abacus-flashcards/commit/ad1ad690f014257b5a3c3f599e794205a11d286f))
+
+## [4.60.0](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.59.1...v4.60.0) (2025-10-21)
+
+
+### Features
+
+* **homepage:** significantly increase mobile hero abacus size ([424f41d](https://github.com/antialias/soroban-abacus-flashcards/commit/424f41d4bfc1ddea068f8c110b495ebd5c0bb455))
+
+## [4.59.1](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.59.0...v4.59.1) (2025-10-21)
+
+
+### Bug Fixes
+
+* **homepage:** adjust hero abacus scale for optimal sizing across devices ([86dee31](https://github.com/antialias/soroban-abacus-flashcards/commit/86dee31c9a51ca0712f1b4181a4899d25374d403))
+* **homepage:** reduce mobile abacus scale to prevent scroll hint overlap ([b8235be](https://github.com/antialias/soroban-abacus-flashcards/commit/b8235be612c3f1dbd0da2b6cd1a935001b7dac9b))
+
+## [4.59.0](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.58.2...v4.59.0) (2025-10-21)
+
+
+### Features
+
+* **homepage:** increase hero abacus size for better visibility ([7666b0a](https://github.com/antialias/soroban-abacus-flashcards/commit/7666b0aea949f2432a4d0f4648c1a366af3ea6d2))
+
+## [4.58.2](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.58.1...v4.58.2) (2025-10-21)
+
+
+### Code Refactoring
+
+* **navbar:** prevent subtitle wrap and remove abacus emoji ([a58f7b7](https://github.com/antialias/soroban-abacus-flashcards/commit/a58f7b78b0020c85da523c36fdf6d70ad069736a))
+
+## [4.58.1](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.58.0...v4.58.1) (2025-10-21)
+
+
+### Bug Fixes
+
+* **navbar:** apply glassmorphism to transparent mode, not scrolled mode ([8893675](https://github.com/antialias/soroban-abacus-flashcards/commit/8893675b36b1c1534c6fe7e57fa7e0cc55f198d6))
+
+## [4.58.0](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.57.10...v4.58.0) (2025-10-21)
+
+
+### Features
+
+* **navbar:** add glassmorphism effect to nav links when scrolled ([89b9072](https://github.com/antialias/soroban-abacus-flashcards/commit/89b90723b7a3fc9ed12da3ba8718fccb6ce0760f))
+
+## [4.57.10](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.57.9...v4.57.10) (2025-10-21)
+
+
+### Bug Fixes
+
+* **navbar:** remove border artifact and add 10px bottom fade ([d5f60ce](https://github.com/antialias/soroban-abacus-flashcards/commit/d5f60ce9d2fbc2a870b3bb96f5365a0e04e0afc4))
+
+
+### Styles
+
+* **navbar:** improve theming to match homepage dark aesthetic ([284fc90](https://github.com/antialias/soroban-abacus-flashcards/commit/284fc90a53f5f4868a3e41421760ebc813be12b5))
+
+## [4.57.9](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.57.8...v4.57.9) (2025-10-21)
+
+
+### Bug Fixes
+
+* **homepage:** add overflow hidden to Your Journey section ([415a1fb](https://github.com/antialias/soroban-abacus-flashcards/commit/415a1fb1faa263c9d69b4e781ce22da235ca2b66))
+
+## [4.57.8](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.57.7...v4.57.8) (2025-10-21)
+
+
+### Bug Fixes
+
+* **homepage:** adjust responsive breakpoints to prevent skill card clipping ([62ff067](https://github.com/antialias/soroban-abacus-flashcards/commit/62ff067bb956b17a9b3569eadc2a32abd24c27b8))
+
+## [4.57.7](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.57.6...v4.57.7) (2025-10-21)
+
+
+### Bug Fixes
+
+* **homepage:** restructure layout to center 1400px wide demo section ([61403f2](https://github.com/antialias/soroban-abacus-flashcards/commit/61403f2f506557b57716a298d4dc481d7853552f))
+* **homepage:** set min-width 1400px on container and remove max-width ([aa297d4](https://github.com/antialias/soroban-abacus-flashcards/commit/aa297d4ef7559473a147934766bfa3868552f58d))
+
+## [4.57.6](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.57.5...v4.57.6) (2025-10-21)
+
+
+### Bug Fixes
+
+* **homepage:** increase skill cards container width to prevent title wrapping ([cd3eb61](https://github.com/antialias/soroban-abacus-flashcards/commit/cd3eb61cb59e6faef37fbf609f37f7e2dc302e72))
+
+## [4.57.5](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.57.4...v4.57.5) (2025-10-21)
+
+
+### Bug Fixes
+
+* **homepage:** prevent text overflow in skill cards ([a6ac55b](https://github.com/antialias/soroban-abacus-flashcards/commit/a6ac55b7b161e0dd33a4dd5acc0df647b2a513aa))
+
+## [4.57.4](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.57.3...v4.57.4) (2025-10-21)
+
+
+### Bug Fixes
+
+* **homepage:** align container width breakpoint with grid columns ([422bf3d](https://github.com/antialias/soroban-abacus-flashcards/commit/422bf3d968b67e4683ac7ea7e487a84513f992f9))
+* **homepage:** make MiniAbacus fill container properly ([3b5d147](https://github.com/antialias/soroban-abacus-flashcards/commit/3b5d14765dfb2d61a76f66ba3ae09695ce88bb6d))
+* **homepage:** widen skill cards container to 650px ([bc1ad3a](https://github.com/antialias/soroban-abacus-flashcards/commit/bc1ad3a43a79570e1f9c61d5118d14ac4c201d71))
+
+## [4.57.3](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.57.2...v4.57.3) (2025-10-21)
+
+
+### Bug Fixes
+
+* **homepage:** increase abacus container width to 120px/150px ([57c212f](https://github.com/antialias/soroban-abacus-flashcards/commit/57c212f4f5be591f712e1c5610e1f323e56e15dd))
+
 ## [4.57.2](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.57.1...v4.57.2) (2025-10-21)
 
 

apps/web/src/app/arcade/complement-race/components/RaceTrack/GhostTrain.tsx

@@ -0,0 +1,233 @@
+'use client'
+
+import { useSpring, useSprings, animated, to } from '@react-spring/web'
+import { useMemo, useRef } from 'react'
+import type { PlayerState } from '@/arcade-games/complement-race/types'
+import type { RailroadTrackGenerator } from '../../lib/RailroadTrackGenerator'
+
+// Overlap threshold: if ghost car is within this distance of any local car, make it ghostly
+const OVERLAP_THRESHOLD = 20 // % of track length
+const GHOST_OPACITY = 0.35 // Opacity when overlapping
+const SOLID_OPACITY = 1.0 // Opacity when separated
+
+interface GhostTrainProps {
+  player: PlayerState
+  trainPosition: number
+  localTrainCarPositions: number[] // [locomotive, car1, car2, car3]
+  maxCars: number
+  carSpacing: number
+  trackGenerator: RailroadTrackGenerator
+  pathRef: React.RefObject<SVGPathElement>
+}
+
+interface CarTransform {
+  x: number
+  y: number
+  rotation: number
+  opacity: number
+  position: number
+}
+
+/**
+ * Calculate opacity for a ghost car based on distance to nearest local car
+ */
+function calculateCarOpacity(ghostCarPosition: number, localCarPositions: number[]): number {
+  // Find minimum distance to any local car
+  const minDistance = Math.min(
+    ...localCarPositions.map((localPos) => Math.abs(ghostCarPosition - localPos))
+  )
+
+  // If within threshold, use ghost opacity; otherwise solid
+  return minDistance < OVERLAP_THRESHOLD ? GHOST_OPACITY : SOLID_OPACITY
+}
+
+/**
+ * GhostTrain - Renders a semi-transparent train for other players in multiplayer
+ * Uses per-car adaptive opacity: cars are ghostly when overlapping local train,
+ * solid when separated
+ */
+export function GhostTrain({
+  player,
+  trainPosition,
+  localTrainCarPositions,
+  maxCars,
+  carSpacing,
+  trackGenerator,
+  pathRef,
+}: GhostTrainProps) {
+  const ghostRef = useRef<SVGGElement>(null)
+
+  // Calculate target transform for locomotive (used by spring animation)
+  const locomotiveTarget = useMemo<CarTransform | null>(() => {
+    if (!pathRef.current) {
+      return null
+    }
+
+    const pathLength = pathRef.current.getTotalLength()
+    const targetDistance = (trainPosition / 100) * pathLength
+    const point = pathRef.current.getPointAtLength(targetDistance)
+
+    // Calculate tangent for rotation
+    const tangentDelta = 1
+    const tangentDistance = Math.min(targetDistance + tangentDelta, pathLength)
+    const tangentPoint = pathRef.current.getPointAtLength(tangentDistance)
+    const rotation =
+      (Math.atan2(tangentPoint.y - point.y, tangentPoint.x - point.x) * 180) / Math.PI
+
+    return {
+      x: point.x,
+      y: point.y,
+      rotation,
+      position: trainPosition,
+      opacity: calculateCarOpacity(trainPosition, localTrainCarPositions),
+    }
+  }, [trainPosition, localTrainCarPositions, pathRef])
+
+  // Animated spring for smooth locomotive movement
+  const locomotiveSpring = useSpring({
+    x: locomotiveTarget?.x ?? 0,
+    y: locomotiveTarget?.y ?? 0,
+    rotation: locomotiveTarget?.rotation ?? 0,
+    opacity: locomotiveTarget?.opacity ?? 1,
+    config: { tension: 280, friction: 60 }, // Smooth but responsive
+  })
+
+  // Calculate target transforms for cars (used by spring animations)
+  const carTargets = useMemo<CarTransform[]>(() => {
+    if (!pathRef.current) {
+      return []
+    }
+
+    const pathLength = pathRef.current.getTotalLength()
+    const cars: CarTransform[] = []
+
+    for (let i = 0; i < maxCars; i++) {
+      const carPosition = Math.max(0, trainPosition - (i + 1) * carSpacing)
+      const targetDistance = (carPosition / 100) * pathLength
+      const point = pathRef.current.getPointAtLength(targetDistance)
+
+      // Calculate tangent for rotation
+      const tangentDelta = 1
+      const tangentDistance = Math.min(targetDistance + tangentDelta, pathLength)
+      const tangentPoint = pathRef.current.getPointAtLength(tangentDistance)
+      const rotation =
+        (Math.atan2(tangentPoint.y - point.y, tangentPoint.x - point.x) * 180) / Math.PI
+
+      cars.push({
+        x: point.x,
+        y: point.y,
+        rotation,
+        position: carPosition,
+        opacity: calculateCarOpacity(carPosition, localTrainCarPositions),
+      })
+    }
+
+    return cars
+  }, [trainPosition, maxCars, carSpacing, localTrainCarPositions, pathRef])
+
+  // Animated springs for smooth car movement (useSprings for multiple cars)
+  const carSprings = useSprings(
+    carTargets.length,
+    carTargets.map((target) => ({
+      x: target.x,
+      y: target.y,
+      rotation: target.rotation,
+      opacity: target.opacity,
+      config: { tension: 280, friction: 60 },
+    }))
+  )
+
+  // Don't render if position data isn't ready
+  if (!locomotiveTarget) {
+    return null
+  }
+
+  return (
+    <g ref={ghostRef} data-component="ghost-train" data-player-id={player.id}>
+      {/* Ghost locomotive - animated */}
+      <animated.g
+        transform={to(
+          [locomotiveSpring.x, locomotiveSpring.y, locomotiveSpring.rotation],
+          (x, y, rot) => `translate(${x}, ${y}) rotate(${rot}) scale(-1, 1)`
+        )}
+        opacity={locomotiveSpring.opacity}
+      >
+        <text
+          data-element="ghost-locomotive"
+          x={0}
+          y={0}
+          textAnchor="middle"
+          style={{
+            fontSize: '100px',
+            filter: `drop-shadow(0 2px 8px ${player.color || 'rgba(100, 100, 255, 0.6)'})`,
+            pointerEvents: 'none',
+          }}
+        >
+          🚂
+        </text>
+
+        {/* Player name label - positioned above locomotive */}
+        <text
+          data-element="ghost-label"
+          x={0}
+          y={-60}
+          textAnchor="middle"
+          style={{
+            fontSize: '18px',
+            fontWeight: 'bold',
+            fill: player.color || '#6366f1',
+            filter: 'drop-shadow(0 1px 2px rgba(0, 0, 0, 0.3))',
+            pointerEvents: 'none',
+            transform: 'scaleX(-1)', // Counter the parent's scaleX(-1)
+          }}
+        >
+          {player.name || `Player ${player.id.slice(0, 4)}`}
+        </text>
+
+        {/* Score indicator - positioned below locomotive */}
+        <text
+          data-element="ghost-score"
+          x={0}
+          y={50}
+          textAnchor="middle"
+          style={{
+            fontSize: '14px',
+            fontWeight: 'bold',
+            fill: 'rgba(255, 255, 255, 0.9)',
+            filter: 'drop-shadow(0 1px 2px rgba(0, 0, 0, 0.5))',
+            pointerEvents: 'none',
+            transform: 'scaleX(-1)', // Counter the parent's scaleX(-1)
+          }}
+        >
+          {player.score}
+        </text>
+      </animated.g>
+
+      {/* Ghost cars - each with individual animated opacity and position */}
+      {carSprings.map((spring, index) => (
+        <animated.g
+          key={`car-${index}`}
+          transform={to(
+            [spring.x, spring.y, spring.rotation],
+            (x, y, rot) => `translate(${x}, ${y}) rotate(${rot}) scale(-1, 1)`
+          )}
+          opacity={spring.opacity}
+        >
+          <text
+            data-element={`ghost-car-${index}`}
+            x={0}
+            y={0}
+            textAnchor="middle"
+            style={{
+              fontSize: '85px',
+              filter: `drop-shadow(0 2px 6px ${player.color || 'rgba(100, 100, 255, 0.4)'})`,
+              pointerEvents: 'none',
+            }}
+          >
+            🚃
+          </text>
+        </animated.g>
+      ))}
+    </g>
+  )
+}

apps/web/src/app/arcade/complement-race/components/RaceTrack/SteamTrainJourney.tsx

@@ -20,6 +20,7 @@ import { GameHUD } from './GameHUD'
 import { RailroadTrackPath } from './RailroadTrackPath'
 import { TrainAndCars } from './TrainAndCars'
 import { TrainTerrainBackground } from './TrainTerrainBackground'
+import { GhostTrain } from './GhostTrain'
 
 const BoardingPassengerAnimation = memo(({ animation }: { animation: BoardingAnimation }) => {
   const spring = useSpring({
@@ -92,7 +93,7 @@ export function SteamTrainJourney({
   currentQuestion,
   currentInput,
 }: SteamTrainJourneyProps) {
-  const { state } = useComplementRace()
+  const { state, multiplayerState, localPlayerId } = useComplementRace()
 
   const { getSkyGradient, getTimeOfDayPeriod } = useSteamJourney()
   const _skyGradient = getSkyGradient()
@@ -100,10 +101,10 @@ export function SteamTrainJourney({
   const { players } = useGameMode()
   const { profile: _profile } = useUserProfile()
 
-  // Get the first active player's emoji
-  const activePlayers = Array.from(players.values()).filter((p) => p.id)
-  const firstActivePlayer = activePlayers[0]
-  const playerEmoji = firstActivePlayer?.emoji ?? '👤'
+  // Get the LOCAL player's emoji (not just the first player!)
+  const activePlayers = Array.from(players.values()).filter((p) => p.isActive)
+  const localPlayer = activePlayers.find((p) => p.isLocal)
+  const playerEmoji = localPlayer?.emoji ?? '👤'
 
   const svgRef = useRef<SVGSVGElement>(null)
   const pathRef = useRef<SVGPathElement>(null)
@@ -164,9 +165,13 @@ export function SteamTrainJourney({
 
   // Memoize filtered passenger lists to avoid recalculating on every render
   // Arcade room multiplayer uses claimedBy/deliveredBy instead of isBoarded/isDelivered
+  // Only show passengers claimed by the LOCAL player
   const boardedPassengers = useMemo(
-    () => displayPassengers.filter((p) => p.claimedBy !== null && p.deliveredBy === null),
-    [displayPassengers]
+    () =>
+      displayPassengers.filter(
+        (p) => p.claimedBy === localPlayer?.id && p.claimedBy !== null && p.deliveredBy === null
+      ),
+    [displayPassengers, localPlayer?.id]
   )
 
   const nonDeliveredPassengers = useMemo(
@@ -186,6 +191,29 @@ export function SteamTrainJourney({
     []
   )
 
+  // Calculate local train car positions for ghost train overlap detection
+  // Array includes locomotive + all cars: [locomotive, car1, car2, car3]
+  const localTrainCarPositions = useMemo(() => {
+    const positions = [trainPosition] // Locomotive at front
+    for (let i = 0; i < maxCars; i++) {
+      positions.push(Math.max(0, trainPosition - (i + 1) * carSpacing))
+    }
+    return positions
+  }, [trainPosition, maxCars, carSpacing])
+
+  // Get other players for ghost trains (filter out local player)
+  const otherPlayers = useMemo(() => {
+    if (!multiplayerState?.players || !localPlayerId) {
+      return []
+    }
+
+    const filtered = Object.entries(multiplayerState.players)
+      .filter(([playerId, player]) => playerId !== localPlayerId && player.isActive)
+      .map(([_, player]) => player)
+
+    return filtered
+  }, [multiplayerState?.players, localPlayerId])
+
   if (!trackData) return null
 
   return (
@@ -247,7 +275,21 @@ export function SteamTrainJourney({
           disembarkingAnimations={disembarkingAnimations}
         />
 
-        {/* Train, cars, and passenger animations */}
+        {/* Ghost trains - other players in multiplayer */}
+        {otherPlayers.map((player) => (
+          <GhostTrain
+            key={player.id}
+            player={player}
+            trainPosition={player.position} // Use each player's individual position
+            localTrainCarPositions={localTrainCarPositions} // For per-car overlap detection
+            maxCars={maxCars}
+            carSpacing={carSpacing}
+            trackGenerator={trackGenerator}
+            pathRef={pathRef}
+          />
+        ))}
+
+        {/* Train, cars, and passenger animations - local player */}
         <TrainAndCars
           boardingAnimations={boardingAnimations}
           disembarkingAnimations={disembarkingAnimations}

apps/web/src/app/arcade/complement-race/hooks/useSteamJourney.ts

@@ -34,7 +34,7 @@ const MOMENTUM_DECAY_RATES = {
 
 const MOMENTUM_GAIN_PER_CORRECT = 15 // Momentum added for each correct answer
 const SPEED_MULTIPLIER = 0.15 // Convert momentum to speed (% per second at momentum=100)
-const UPDATE_INTERVAL = 50 // Update every 50ms (~20 fps)
+const UPDATE_INTERVAL = 16 // Update every 16ms (~60 fps for smooth animation)
 const GAME_DURATION = 60000 // 60 seconds in milliseconds
 
 export function useSteamJourney() {

apps/web/src/app/arcade/complement-race/hooks/useTrackManagement.ts

@@ -104,7 +104,9 @@ export function useTrackManagement({
       setDisplayPassengers(passengers)
     }
     // Otherwise, keep displaying old passengers until train resets
-  }, [passengers, displayPassengers, trainPosition, currentRoute])
+    // Note: displayPassengers is intentionally NOT in deps to avoid infinite loop
+    // (it's used for comparison, but we don't need to re-run when it changes)
+  }, [passengers, trainPosition, currentRoute])
 
   // Generate ties and rails when path is ready
   useEffect(() => {

apps/web/src/app/page.tsx

@@ -54,14 +54,14 @@ function MiniAbacus({
   return (
     <div
       className={css({
-        width: '75px',
-        height: '80px',
+        width: '100%',
+        height: '100%',
         display: 'flex',
         alignItems: 'center',
         justifyContent: 'center',
       })}
     >
-      <div className={css({ transform: 'scale(0.6)', transformOrigin: 'center center' })}>
+      <div className={css({ transform: 'scale(0.75)', transformOrigin: 'center center' })}>
         <AbacusReact
           value={values[currentIndex] || 0}
           columns={columns}
@@ -122,233 +122,239 @@ export default function HomePage() {
           {/* Hero Section with Large Interactive Abacus */}
           <HeroAbacus />
 
-          {/* Main content container */}
-          <div className={container({ maxW: '7xl', px: '4', py: '12' })}>
-            {/* Learn by Doing Section - with inline tutorial demo */}
-            <section className={stack({ gap: '8', mb: '16' })}>
-              <div className={css({ textAlign: 'center' })}>
-                <h2
-                  className={css({
-                    fontSize: { base: '2xl', md: '3xl' },
-                    fontWeight: 'bold',
-                    color: 'white',
-                    mb: '2',
-                  })}
-                >
-                  Learn by Doing
-                </h2>
-                <p className={css({ color: 'gray.400', fontSize: 'md', maxW: '2xl', mx: 'auto' })}>
-                  Interactive tutorials teach you step-by-step. Try this example right now:
-                </p>
-              </div>
-
-              {/* Live demo and learning objectives */}
-              <div
+          {/* Learn by Doing Section - with inline tutorial demo */}
+          <section className={stack({ gap: '8', mb: '16', px: '4', py: '12' })}>
+            <div className={css({ textAlign: 'center' })}>
+              <h2
                 className={css({
-                  bg: 'rgba(0, 0, 0, 0.4)',
-                  rounded: 'xl',
-                  p: '8',
-                  border: '1px solid',
-                  borderColor: 'gray.700',
-                  shadow: 'lg',
-                  maxW: '1200px',
-                  mx: 'auto',
+                  fontSize: { base: '2xl', md: '3xl' },
+                  fontWeight: 'bold',
+                  color: 'white',
+                  mb: '2',
                 })}
               >
+                Learn by Doing
+              </h2>
+              <p className={css({ color: 'gray.400', fontSize: 'md', maxW: '2xl', mx: 'auto' })}>
+                Interactive tutorials teach you step-by-step. Try this example right now:
+              </p>
+            </div>
+
+            {/* Live demo and learning objectives */}
+            <div
+              className={css({
+                bg: 'rgba(0, 0, 0, 0.4)',
+                rounded: 'xl',
+                p: '8',
+                border: '1px solid',
+                borderColor: 'gray.700',
+                shadow: 'lg',
+                minW: { base: '100%', xl: '1400px' },
+                mx: 'auto',
+              })}
+            >
+              <div
+                className={css({
+                  display: 'flex',
+                  flexDirection: { base: 'column', xl: 'row' },
+                  gap: '8',
+                  alignItems: { base: 'center', xl: 'flex-start' },
+                })}
+              >
+                {/* Tutorial on the left */}
                 <div
                   className={css({
-                    display: 'flex',
-                    flexDirection: { base: 'column', md: 'row' },
-                    gap: '8',
-                    alignItems: { base: 'center', md: 'flex-start' },
+                    flex: '1',
+                    minW: { base: '100%', xl: '500px' },
+                    maxW: { base: '100%', xl: '500px' },
                   })}
                 >
-                  {/* Tutorial on the left */}
-                  <div
-                    className={css({
-                      flex: '1',
-                      minW: { base: '100%', md: '500px' },
-                      maxW: { base: '100%', md: '500px' },
-                    })}
-                  >
-                    <TutorialPlayer
-                      key={selectedTutorial.id}
-                      tutorial={selectedTutorial}
-                      isDebugMode={false}
-                      showDebugPanel={false}
-                      hideNavigation={true}
-                      hideTooltip={true}
-                      silentErrors={true}
-                      abacusColumns={1}
-                      theme="dark"
-                    />
-                  </div>
+                  <TutorialPlayer
+                    key={selectedTutorial.id}
+                    tutorial={selectedTutorial}
+                    isDebugMode={false}
+                    showDebugPanel={false}
+                    hideNavigation={true}
+                    hideTooltip={true}
+                    silentErrors={true}
+                    abacusColumns={1}
+                    theme="dark"
+                  />
+                </div>
 
-                  {/* What you'll learn on the right */}
-                  <div
+                {/* What you'll learn on the right */}
+                <div
+                  className={css({
+                    flex: '0 0 auto',
+                    w: { base: '100%', lg: '800px' },
+                  })}
+                >
+                  <h3
                     className={css({
-                      flex: '0 0 auto',
-                      w: { base: '100%', md: '420px' },
+                      fontSize: '2xl',
+                      fontWeight: 'bold',
+                      color: 'white',
+                      mb: '6',
                     })}
                   >
-                    <h3
-                      className={css({
-                        fontSize: '2xl',
-                        fontWeight: 'bold',
-                        color: 'white',
-                        mb: '6',
-                      })}
-                    >
-                      What You'll Learn
-                    </h3>
-                    <div className={grid({ columns: { base: 1, lg: 2 }, gap: '5' })}>
-                      {[
-                        {
-                          title: '📖 Read and set numbers',
-                          desc: 'Master abacus number representation from zero to thousands',
-                          example: '0-9999',
-                          badge: 'Foundation',
-                          values: [0, 1, 2, 3, 4, 5, 10, 50, 100, 500, 999],
-                          columns: 3,
-                        },
-                        {
-                          title: '🤝 Friends techniques',
-                          desc: 'Add and subtract using complement pairs and mental shortcuts',
-                          example: '5 = 2+3',
-                          badge: 'Core',
-                          values: [2, 5, 3],
-                          columns: 1,
-                        },
-                        {
-                          title: '✖️ Multiply & divide',
-                          desc: 'Fluent multi-digit calculations with advanced techniques',
-                          example: '12×34',
-                          badge: 'Advanced',
-                          values: [12, 24, 36, 48],
-                          columns: 2,
-                        },
-                        {
-                          title: '🧠 Mental calculation',
-                          desc: 'Visualize and compute without the physical tool (Anzan)',
-                          example: 'Speed math',
-                          badge: 'Expert',
-                          values: [7, 14, 21, 28, 35],
-                          columns: 2,
-                        },
-                      ].map((skill, i) => {
-                        const isSelected = i === selectedSkillIndex
-                        return (
-                          <div
-                            key={i}
-                            onClick={() => setSelectedSkillIndex(i)}
-                            className={css({
+                    What You'll Learn
+                  </h3>
+                  <div className={grid({ columns: { base: 1, lg: 2 }, gap: '5' })}>
+                    {[
+                      {
+                        title: '📖 Read and set numbers',
+                        desc: 'Master abacus number representation from zero to thousands',
+                        example: '0-9999',
+                        badge: 'Foundation',
+                        values: [0, 1, 2, 3, 4, 5, 10, 50, 100, 500, 999],
+                        columns: 3,
+                      },
+                      {
+                        title: '🤝 Friends techniques',
+                        desc: 'Add and subtract using complement pairs and mental shortcuts',
+                        example: '5 = 2+3',
+                        badge: 'Core',
+                        values: [2, 5, 3],
+                        columns: 1,
+                      },
+                      {
+                        title: '✖️ Multiply & divide',
+                        desc: 'Fluent multi-digit calculations with advanced techniques',
+                        example: '12×34',
+                        badge: 'Advanced',
+                        values: [12, 24, 36, 48],
+                        columns: 2,
+                      },
+                      {
+                        title: '🧠 Mental calculation',
+                        desc: 'Visualize and compute without the physical tool (Anzan)',
+                        example: 'Speed math',
+                        badge: 'Expert',
+                        values: [7, 14, 21, 28, 35],
+                        columns: 2,
+                      },
+                    ].map((skill, i) => {
+                      const isSelected = i === selectedSkillIndex
+                      return (
+                        <div
+                          key={i}
+                          onClick={() => setSelectedSkillIndex(i)}
+                          className={css({
+                            bg: isSelected
+                              ? 'linear-gradient(135deg, rgba(250, 204, 21, 0.15), rgba(250, 204, 21, 0.08))'
+                              : 'linear-gradient(135deg, rgba(255, 255, 255, 0.06), rgba(255, 255, 255, 0.03))',
+                            borderRadius: 'xl',
+                            p: { base: '4', lg: '5' },
+                            border: '1px solid',
+                            borderColor: isSelected
+                              ? 'rgba(250, 204, 21, 0.4)'
+                              : 'rgba(255, 255, 255, 0.15)',
+                            boxShadow: isSelected
+                              ? '0 6px 16px rgba(250, 204, 21, 0.2)'
+                              : '0 4px 12px rgba(0, 0, 0, 0.3)',
+                            transition: 'all 0.2s',
+                            cursor: 'pointer',
+                            _hover: {
                               bg: isSelected
-                                ? 'linear-gradient(135deg, rgba(250, 204, 21, 0.15), rgba(250, 204, 21, 0.08))'
-                                : 'linear-gradient(135deg, rgba(255, 255, 255, 0.06), rgba(255, 255, 255, 0.03))',
-                              borderRadius: 'xl',
-                              p: { base: '4', lg: '5' },
-                              border: '1px solid',
+                                ? 'linear-gradient(135deg, rgba(250, 204, 21, 0.2), rgba(250, 204, 21, 0.12))'
+                                : 'linear-gradient(135deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0.05))',
                               borderColor: isSelected
-                                ? 'rgba(250, 204, 21, 0.4)'
-                                : 'rgba(255, 255, 255, 0.15)',
+                                ? 'rgba(250, 204, 21, 0.5)'
+                                : 'rgba(255, 255, 255, 0.25)',
+                              transform: 'translateY(-2px)',
                               boxShadow: isSelected
-                                ? '0 6px 16px rgba(250, 204, 21, 0.2)'
-                                : '0 4px 12px rgba(0, 0, 0, 0.3)',
-                              transition: 'all 0.2s',
-                              cursor: 'pointer',
-                              _hover: {
+                                ? '0 8px 20px rgba(250, 204, 21, 0.3)'
+                                : '0 6px 16px rgba(0, 0, 0, 0.4)',
+                            },
+                          })}
+                        >
+                          <div className={hstack({ gap: '3', alignItems: 'flex-start' })}>
+                            <div
+                              className={css({
+                                fontSize: '3xl',
+                                width: { base: '120px', lg: '150px' },
+                                minHeight: { base: '115px', lg: '140px' },
+                                display: 'flex',
+                                alignItems: 'center',
+                                justifyContent: 'center',
+                                textAlign: 'center',
                                 bg: isSelected
-                                  ? 'linear-gradient(135deg, rgba(250, 204, 21, 0.2), rgba(250, 204, 21, 0.12))'
-                                  : 'linear-gradient(135deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0.05))',
-                                borderColor: isSelected
-                                  ? 'rgba(250, 204, 21, 0.5)'
-                                  : 'rgba(255, 255, 255, 0.25)',
-                                transform: 'translateY(-2px)',
-                                boxShadow: isSelected
-                                  ? '0 8px 20px rgba(250, 204, 21, 0.3)'
-                                  : '0 6px 16px rgba(0, 0, 0, 0.4)',
-                              },
-                            })}
-                          >
-                            <div className={hstack({ gap: '3', alignItems: 'flex-start' })}>
+                                  ? 'rgba(250, 204, 21, 0.15)'
+                                  : 'rgba(255, 255, 255, 0.1)',
+                                borderRadius: 'lg',
+                              })}
+                            >
+                              <MiniAbacus values={skill.values} columns={skill.columns} />
+                            </div>
+                            <div className={stack({ gap: '2', flex: '1', minWidth: '0' })}>
                               <div
-                                className={css({
-                                  fontSize: '3xl',
-                                  width: { base: '95px', lg: '110px' },
-                                  minHeight: { base: '115px', lg: '140px' },
-                                  display: 'flex',
+                                className={hstack({
+                                  gap: '2',
                                   alignItems: 'center',
-                                  justifyContent: 'center',
-                                  textAlign: 'center',
-                                  bg: isSelected
-                                    ? 'rgba(250, 204, 21, 0.15)'
-                                    : 'rgba(255, 255, 255, 0.1)',
-                                  borderRadius: 'lg',
+                                  flexWrap: 'wrap',
                                 })}
                               >
-                                <MiniAbacus values={skill.values} columns={skill.columns} />
-                              </div>
-                              <div className={stack({ gap: '2', flex: '1' })}>
-                                <div className={hstack({ gap: '2', alignItems: 'center' })}>
-                                  <div
-                                    className={css({
-                                      color: 'white',
-                                      fontSize: 'md',
-                                      fontWeight: 'bold',
-                                    })}
-                                  >
-                                    {skill.title}
-                                  </div>
-                                  <div
-                                    className={css({
-                                      bg: 'rgba(250, 204, 21, 0.2)',
-                                      color: 'yellow.400',
-                                      fontSize: '2xs',
-                                      fontWeight: 'semibold',
-                                      px: '2',
-                                      py: '0.5',
-                                      borderRadius: 'md',
-                                    })}
-                                  >
-                                    {skill.badge}
-                                  </div>
-                                </div>
                                 <div
                                   className={css({
-                                    color: 'gray.300',
-                                    fontSize: 'xs',
-                                    lineHeight: '1.5',
+                                    color: 'white',
+                                    fontSize: 'md',
+                                    fontWeight: 'bold',
                                   })}
                                 >
-                                  {skill.desc}
+                                  {skill.title}
                                 </div>
                                 <div
                                   className={css({
+                                    bg: 'rgba(250, 204, 21, 0.2)',
                                     color: 'yellow.400',
-                                    fontSize: 'xs',
-                                    fontFamily: 'mono',
+                                    fontSize: '2xs',
                                     fontWeight: 'semibold',
-                                    mt: '1',
-                                    bg: 'rgba(250, 204, 21, 0.1)',
                                     px: '2',
-                                    py: '1',
+                                    py: '0.5',
                                     borderRadius: 'md',
-                                    w: 'fit-content',
                                   })}
                                 >
-                                  {skill.example}
+                                  {skill.badge}
                                 </div>
                               </div>
+                              <div
+                                className={css({
+                                  color: 'gray.300',
+                                  fontSize: 'xs',
+                                  lineHeight: '1.5',
+                                })}
+                              >
+                                {skill.desc}
+                              </div>
+                              <div
+                                className={css({
+                                  color: 'yellow.400',
+                                  fontSize: 'xs',
+                                  fontFamily: 'mono',
+                                  fontWeight: 'semibold',
+                                  mt: '1',
+                                  bg: 'rgba(250, 204, 21, 0.1)',
+                                  px: '2',
+                                  py: '1',
+                                  borderRadius: 'md',
+                                  w: 'fit-content',
+                                })}
+                              >
+                                {skill.example}
+                              </div>
                             </div>
                           </div>
-                        )
-                      })}
-                    </div>
+                        </div>
+                      )
+                    })}
                   </div>
                 </div>
               </div>
-            </section>
+            </div>
+          </section>
 
+          {/* Main content container */}
+          <div className={container({ maxW: '7xl', px: '4', py: '12' })}>
             {/* Current Offerings Section */}
             <section className={stack({ gap: '6', mb: '16' })}>
               <div className={css({ textAlign: 'center' })}>
@@ -391,7 +397,7 @@ export default function HomePage() {
             </section>
 
             {/* Progression Visualization */}
-            <section className={stack({ gap: '6', mb: '16' })}>
+            <section className={stack({ gap: '6', mb: '16', overflow: 'hidden' })}>
               <div className={css({ textAlign: 'center' })}>
                 <h2
                   className={css({

apps/web/src/arcade-games/complement-race/Provider.tsx

@@ -99,6 +99,8 @@ interface CompatibleGameState {
  */
 interface ComplementRaceContextValue {
   state: CompatibleGameState // Return adapted state
+  multiplayerState: ComplementRaceState // Raw multiplayer state for rendering other players
+  localPlayerId: string | undefined // Local player ID for filtering
   dispatch: (action: { type: string; [key: string]: any }) => void // Compatibility layer
   lastError: string | null
   startGame: () => void
@@ -304,19 +306,35 @@ export function ComplementRaceProvider({ children }: { children: ReactNode }) {
 
   // Get local player ID
   const localPlayerId = useMemo(() => {
-    return activePlayers.find((id) => {
+    const foundId = activePlayers.find((id) => {
       const player = players.get(id)
       return player?.isLocal
     })
+    return foundId
   }, [activePlayers, players])
 
-  // Debug logging ref (track last logged values)
-  const lastLogRef = useState({ key: '', count: 0 })[0]
-
   // Client-side game state (NOT synced to server - purely visual/gameplay)
   const [clientMomentum, setClientMomentum] = useState(10) // Start at 10 for gentle push
   const [clientPosition, setClientPosition] = useState(0)
   const [clientPressure, setClientPressure] = useState(0)
+
+  // Track if we've synced position from server (for reconnect/reload scenarios)
+  const hasInitializedPositionRef = useRef(false)
+
+  // Ref to track latest position for broadcasting (avoids recreating interval on every position change)
+  const clientPositionRef = useRef(clientPosition)
+
+  // Refs for throttled logging
+  const lastBroadcastLogRef = useRef({ position: 0, time: 0 })
+  const broadcastCountRef = useRef(0)
+  const lastReceivedPositionsRef = useRef<Record<string, number>>({})
+
+  // Ref to hold sendMove so interval doesn't restart when sendMove changes
+  const sendMoveRef = useRef(sendMove)
+  useEffect(() => {
+    sendMoveRef.current = sendMove
+  }, [sendMove])
+
   const [clientAIRacers, setClientAIRacers] = useState<
     Array<{
       id: string
@@ -347,7 +365,7 @@ export function ComplementRaceProvider({ children }: { children: ReactNode }) {
   const MOMENTUM_GAIN_PER_CORRECT = 15
   const MOMENTUM_LOSS_PER_WRONG = 10
   const SPEED_MULTIPLIER = 0.15 // momentum * 0.15 = % per second
-  const UPDATE_INTERVAL = 50 // 50ms = ~20fps
+  const UPDATE_INTERVAL = 16 // 16ms = ~60fps for smooth animation
 
   // Transform multiplayer state to look like single-player state
   const compatibleState = useMemo((): CompatibleGameState => {
@@ -443,16 +461,50 @@ export function ComplementRaceProvider({ children }: { children: ReactNode }) {
     clientAIRacers,
   ])
 
+  // Sync client position from server on reconnect/reload (multiplayer only)
+  useEffect(() => {
+    // Only sync if:
+    // 1. We haven't synced yet
+    // 2. Game is active
+    // 3. We're in sprint mode
+    // 4. We have a local player with a position from server
+    if (
+      !hasInitializedPositionRef.current &&
+      multiplayerState.gamePhase === 'playing' &&
+      multiplayerState.config.style === 'sprint' &&
+      localPlayerId
+    ) {
+      const serverPosition = multiplayerState.players[localPlayerId]?.position
+      if (serverPosition !== undefined && serverPosition > 0) {
+        console.log(`[POSITION_SYNC] Restoring position from server: ${serverPosition.toFixed(1)}%`)
+        setClientPosition(serverPosition)
+        hasInitializedPositionRef.current = true
+      }
+    }
+
+    // Reset sync flag when game ends
+    if (multiplayerState.gamePhase !== 'playing') {
+      hasInitializedPositionRef.current = false
+    }
+  }, [
+    multiplayerState.gamePhase,
+    multiplayerState.config.style,
+    multiplayerState.players,
+    localPlayerId,
+  ])
+
   // Initialize game start time when game becomes active
   useEffect(() => {
     if (compatibleState.isGameActive && compatibleState.style === 'sprint') {
       if (gameStartTimeRef.current === 0) {
         gameStartTimeRef.current = Date.now()
         lastUpdateRef.current = Date.now()
-        // Reset client state for new game
-        setClientMomentum(10) // Start with gentle push
-        setClientPosition(0)
-        setClientPressure((10 / 100) * 150) // Initial pressure from starting momentum
+        // Reset client state for new game (only if not restored from server)
+        if (!hasInitializedPositionRef.current) {
+          setClientMomentum(10) // Start with gentle push
+          setClientPosition(0)
+          setClientPressure((10 / 100) * 150) // Initial pressure from starting momentum
+        }
       }
     } else {
       // Reset when game ends
@@ -548,14 +600,78 @@ export function ComplementRaceProvider({ children }: { children: ReactNode }) {
     const currentRoute = multiplayerState.currentRoute
     // When route changes, reset position and give starting momentum
     if (currentRoute > 1 && compatibleState.style === 'sprint') {
-      console.log(
-        `[Provider] Route changed to ${currentRoute}, resetting position. Passengers: ${multiplayerState.passengers.length}`
-      )
       setClientPosition(0)
       setClientMomentum(10) // Reset to starting momentum (gentle push)
     }
   }, [multiplayerState.currentRoute, compatibleState.style, multiplayerState.passengers.length])
 
+  // Keep position ref in sync with latest position
+  useEffect(() => {
+    clientPositionRef.current = clientPosition
+  }, [clientPosition])
+
+  // Log when we receive position updates from other players
+  useEffect(() => {
+    if (!multiplayerState?.players || !localPlayerId) return
+
+    Object.entries(multiplayerState.players).forEach(([playerId, player]) => {
+      if (playerId === localPlayerId || !player.isActive) return
+
+      const lastPos = lastReceivedPositionsRef.current[playerId] ?? -1
+      const currentPos = player.position
+
+      // Log when position changes significantly (>2%)
+      if (Math.abs(currentPos - lastPos) > 2) {
+        console.log(
+          `[POS_RECEIVED] ${player.name}: ${currentPos.toFixed(1)}% (was ${lastPos.toFixed(1)}%, delta=${(currentPos - lastPos).toFixed(1)}%)`
+        )
+        lastReceivedPositionsRef.current[playerId] = currentPos
+      }
+    })
+  }, [multiplayerState?.players, localPlayerId])
+
+  // Broadcast position to server for multiplayer ghost trains
+  useEffect(() => {
+    const isGameActive = multiplayerState.gamePhase === 'playing'
+    const isSprint = multiplayerState.config.style === 'sprint'
+
+    if (!isGameActive || !isSprint || !localPlayerId) {
+      return
+    }
+
+    console.log('[POS_BROADCAST] Starting position broadcast interval')
+
+    // Send position update every 16ms (~60fps) for smoother ghost trains (reads from refs to avoid restarting interval)
+    const interval = setInterval(() => {
+      const currentPos = clientPositionRef.current
+      broadcastCountRef.current++
+
+      // Throttled logging: only log when position changes by >2% or every 5 seconds
+      const now = Date.now()
+      const posDiff = Math.abs(currentPos - lastBroadcastLogRef.current.position)
+      const timeDiff = now - lastBroadcastLogRef.current.time
+
+      if (posDiff > 2 || timeDiff > 5000) {
+        console.log(
+          `[POS_BROADCAST] #${broadcastCountRef.current} pos=${currentPos.toFixed(1)}% (delta=${posDiff.toFixed(1)}%)`
+        )
+        lastBroadcastLogRef.current = { position: currentPos, time: now }
+      }
+
+      sendMoveRef.current({
+        type: 'UPDATE_POSITION',
+        playerId: localPlayerId,
+        userId: viewerId || '',
+        data: { position: currentPos },
+      } as ComplementRaceMove)
+    }, 16)
+
+    return () => {
+      console.log(`[POS_BROADCAST] Stopping interval (sent ${broadcastCountRef.current} updates)`)
+      clearInterval(interval)
+    }
+  }, [multiplayerState.gamePhase, multiplayerState.config.style, localPlayerId, viewerId])
+
   // Keep lastLogRef for future debugging needs
   // (removed debug logging)
 
@@ -769,7 +885,6 @@ export function ComplementRaceProvider({ children }: { children: ReactNode }) {
         case 'START_NEW_ROUTE':
           // Send route progression to server
           if (action.routeNumber !== undefined) {
-            console.log(`[Provider] Dispatching START_NEW_ROUTE for route ${action.routeNumber}`)
             sendMove({
               type: 'START_NEW_ROUTE',
               playerId: activePlayers[0] || '',
@@ -914,6 +1029,8 @@ export function ComplementRaceProvider({ children }: { children: ReactNode }) {
 
   const contextValue: ComplementRaceContextValue = {
     state: compatibleState, // Use transformed state
+    multiplayerState, // Expose raw multiplayer state for ghost trains
+    localPlayerId, // Expose local player ID for filtering
     dispatch,
     lastError,
     startGame,

apps/web/src/arcade-games/complement-race/Validator.ts

@@ -97,6 +97,9 @@ export class ComplementRaceValidator
       case 'UPDATE_INPUT':
         return this.validateUpdateInput(state, move.playerId, move.data.input)
 
+      case 'UPDATE_POSITION':
+        return this.validateUpdatePosition(state, move.playerId, move.data.position)
+
       case 'CLAIM_PASSENGER':
         return this.validateClaimPassenger(
           state,
@@ -397,6 +400,39 @@ export class ComplementRaceValidator
     return { valid: true, newState }
   }
 
+  private validateUpdatePosition(
+    state: ComplementRaceState,
+    playerId: string,
+    position: number
+  ): ValidationResult {
+    if (state.gamePhase !== 'playing') {
+      return { valid: false, error: 'Game not in playing phase' }
+    }
+
+    const player = state.players[playerId]
+    if (!player) {
+      return { valid: false, error: 'Player not found' }
+    }
+
+    // Validate position is a reasonable number (0-100)
+    if (typeof position !== 'number' || position < 0 || position > 100) {
+      return { valid: false, error: 'Invalid position value' }
+    }
+
+    const newState: ComplementRaceState = {
+      ...state,
+      players: {
+        ...state.players,
+        [playerId]: {
+          ...player,
+          position,
+        },
+      },
+    }
+
+    return { valid: true, newState }
+  }
+
   // ==========================================================================
   // Sprint Mode: Passenger Management
   // ==========================================================================

apps/web/src/arcade-games/complement-race/types.ts

@@ -143,6 +143,7 @@ export type ComplementRaceMove = BaseGameMove &
     // Playing phase
     | { type: 'SUBMIT_ANSWER'; data: { answer: number; responseTime: number } }
     | { type: 'UPDATE_INPUT'; data: { input: string } } // Show "thinking" indicator
+    | { type: 'UPDATE_POSITION'; data: { position: number } } // Sprint mode: sync train position
     | { type: 'CLAIM_PASSENGER'; data: { passengerId: string; carIndex: number } } // Sprint mode: pickup
     | { type: 'DELIVER_PASSENGER'; data: { passengerId: string } } // Sprint mode: delivery
 

apps/web/src/components/AppNavBar.tsx

@@ -576,10 +576,11 @@ export function AppNavBar({ variant = 'full', navSlot }: AppNavBarProps) {
     <Tooltip.Provider delayDuration={200}>
       <header
         className={css({
-          bg: isTransparent ? 'transparent' : 'white',
-          shadow: isTransparent ? 'none' : 'sm',
+          bg: isTransparent ? 'transparent' : 'rgba(0, 0, 0, 0.5)',
+          backdropFilter: isTransparent ? 'none' : 'blur(12px)',
+          shadow: isTransparent ? 'none' : 'lg',
           borderBottom: isTransparent ? 'none' : '1px solid',
-          borderColor: isTransparent ? 'transparent' : 'gray.200',
+          borderColor: isTransparent ? 'transparent' : 'rgba(139, 92, 246, 0.2)',
           position: 'fixed',
           top: 0,
           left: 0,
@@ -599,7 +600,7 @@ export function AppNavBar({ variant = 'full', navSlot }: AppNavBarProps) {
                   flexDirection: 'column',
                   gap: '0',
                   textDecoration: 'none',
-                  _hover: { '& > .brand-name': { color: 'brand.900' } },
+                  _hover: { '& > .brand-name': { color: 'rgba(196, 181, 253, 1)' } },
                   opacity: 0,
                   animation: 'fadeIn 0.3s ease-out forwards',
                 })}
@@ -608,10 +609,10 @@ export function AppNavBar({ variant = 'full', navSlot }: AppNavBarProps) {
                   className={css({
                     fontSize: 'xl',
                     fontWeight: 'bold',
-                    color: 'brand.800',
+                    color: 'rgba(255, 255, 255, 0.95)',
                   })}
                 >
-                  🧮 Abaci One
+                  Abaci One
                 </span>
                 <Tooltip.Root>
                   <Tooltip.Trigger asChild>
@@ -619,10 +620,11 @@ export function AppNavBar({ variant = 'full', navSlot }: AppNavBarProps) {
                       className={css({
                         fontSize: 'xs',
                         fontWeight: 'medium',
-                        color: 'brand.600',
+                        color: 'rgba(196, 181, 253, 0.8)',
                         fontStyle: 'italic',
                         cursor: 'help',
-                        _hover: { color: 'brand.700' },
+                        whiteSpace: 'nowrap',
+                        _hover: { color: 'rgba(196, 181, 253, 1)' },
                       })}
                     >
                       {subtitle.text}
@@ -717,6 +719,9 @@ function NavLink({
   return (
     <Link
       href={href}
+      style={{
+        backdropFilter: isTransparent ? 'blur(8px)' : 'none',
+      }}
       className={css({
         px: { base: '4', md: '3' },
         py: { base: '3', md: '2' },
@@ -729,24 +734,33 @@ function NavLink({
             ? 'white'
             : 'rgba(255, 255, 255, 0.8)'
           : isActive
-            ? 'brand.700'
-            : 'gray.600',
+            ? 'rgba(196, 181, 253, 1)'
+            : 'rgba(209, 213, 219, 0.9)',
         bg: isTransparent
           ? isActive
-            ? 'rgba(255, 255, 255, 0.15)'
-            : 'transparent'
+            ? 'rgba(255, 255, 255, 0.2)'
+            : 'rgba(255, 255, 255, 0.08)'
           : isActive
-            ? 'brand.50'
+            ? 'rgba(139, 92, 246, 0.2)'
             : 'transparent',
+        border: isTransparent ? '1px solid' : 'none',
+        borderColor: isTransparent
+          ? isActive
+            ? 'rgba(255, 255, 255, 0.3)'
+            : 'rgba(255, 255, 255, 0.15)'
+          : 'transparent',
         rounded: 'lg',
         transition: 'all',
         textDecoration: 'none',
         display: 'flex',
         alignItems: 'center',
         justifyContent: 'center',
+        boxShadow: isTransparent ? '0 2px 8px rgba(0, 0, 0, 0.2)' : 'none',
         _hover: {
-          color: isTransparent ? 'white' : isActive ? 'brand.800' : 'gray.900',
-          bg: isTransparent ? 'rgba(255, 255, 255, 0.2)' : isActive ? 'brand.100' : 'gray.50',
+          color: isTransparent ? 'white' : 'rgba(196, 181, 253, 1)',
+          bg: isTransparent ? 'rgba(255, 255, 255, 0.25)' : 'rgba(139, 92, 246, 0.25)',
+          borderColor: isTransparent ? 'rgba(255, 255, 255, 0.4)' : 'transparent',
+          boxShadow: isTransparent ? '0 4px 12px rgba(0, 0, 0, 0.3)' : 'none',
         },
       })}
     >

apps/web/src/components/HeroAbacus.tsx

@@ -131,7 +131,7 @@ export function HeroAbacus() {
       >
         <div
           className={css({
-            transform: { base: 'scale(2)', md: 'scale(3)', lg: 'scale(4)' },
+            transform: { base: 'scale(3.5)', md: 'scale(3.5)', lg: 'scale(4.25)' },
             transformOrigin: 'center center',
             transition: 'all 0.5s cubic-bezier(0.4, 0, 0.2, 1)',
           })}

apps/web/src/components/InteractiveFlashcards.tsx

@@ -1,9 +1,7 @@
 'use client'
 
-import { AbacusReact } from '@soroban/abacus-react'
-import { useDrag } from '@use-gesture/react'
+import { AbacusReact, useAbacusConfig } from '@soroban/abacus-react'
 import { useEffect, useRef, useState } from 'react'
-import { animated, config, to, useSpring } from '@react-spring/web'
 import { css } from '../../styled-system/css'
 
 interface Flashcard {
@@ -16,12 +14,11 @@ interface Flashcard {
 }
 
 /**
- * InteractiveFlashcards - A fun, physics-based flashcard display
- * Users can drag and throw flashcards around with realistic momentum
+ * InteractiveFlashcards - A fun flashcard display where you can drag cards around
+ * Cards stay where you drop them - simple and intuitive
  */
 export function InteractiveFlashcards() {
   const containerRef = useRef<HTMLDivElement>(null)
-  // Generate 8-15 random flashcards (client-side only to avoid hydration errors)
   const [cards, setCards] = useState<Flashcard[]>([])
 
   useEffect(() => {
@@ -77,14 +74,14 @@ export function InteractiveFlashcards() {
         maxW: '1200px',
         mx: 'auto',
         height: { base: '400px', md: '500px' },
-        overflow: 'hidden',
+        overflow: 'visible',
         bg: 'rgba(0, 0, 0, 0.3)',
         rounded: 'xl',
         border: '1px solid rgba(255, 255, 255, 0.1)',
       })}
     >
       {cards.map((card) => (
-        <DraggableCard key={card.id} card={card} />
+        <DraggableCard key={card.id} card={card} containerRef={containerRef} />
       ))}
     </div>
   )
@@ -92,193 +89,247 @@ export function InteractiveFlashcards() {
 
 interface DraggableCardProps {
   card: Flashcard
+  containerRef: React.RefObject<HTMLDivElement>
 }
 
-function DraggableCard({ card }: DraggableCardProps) {
-  // Track the card's current position in state (separate from the animation values)
-  const currentPositionRef = useRef({
-    x: card.initialX,
-    y: card.initialY,
-    rotation: card.initialRotation,
-  })
-
-  const [{ x, y, rotation, scale }, api] = useSpring(() => ({
-    x: card.initialX,
-    y: card.initialY,
-    rotation: card.initialRotation,
-    scale: 1,
-    config: config.wobbly,
-  }))
+function DraggableCard({ card, containerRef }: DraggableCardProps) {
+  const appConfig = useAbacusConfig()
 
+  // Track position - starts at initial, updates when dragged
+  const [position, setPosition] = useState({ x: card.initialX, y: card.initialY })
+  const [rotation, setRotation] = useState(card.initialRotation) // Now dynamic!
   const [zIndex, setZIndex] = useState(card.zIndex)
-  const cardRef = useRef<HTMLDivElement>(null)
-  const dragOffsetRef = useRef({ x: 0, y: 0 })
-  const lastVelocityRef = useRef({ vx: 0, vy: 0 })
-  const velocityHistoryRef = useRef<Array<{ vx: number; vy: number }>>([])
-  const [transformOrigin, setTransformOrigin] = useState('center center')
+  const [isDragging, setIsDragging] = useState(false)
+  const [dragSpeed, setDragSpeed] = useState(0) // Speed for dynamic shadow
 
-  const bind = useDrag(
-    ({ down, movement: [mx, my], velocity: [vx, vy], direction: [dx, dy], first, xy }) => {
-      // Bring card to front when dragging
-      if (down) {
-        setZIndex(1000)
+  // Track drag state
+  const dragStartRef = useRef<{ x: number; y: number; cardX: number; cardY: number } | null>(null)
+  const grabOffsetRef = useRef<{ x: number; y: number }>({ x: 0, y: 0 }) // Offset from card center where grabbed
+  const baseRotationRef = useRef(card.initialRotation) // Starting rotation
+  const lastMoveTimeRef = useRef<number>(0)
+  const lastMovePositionRef = useRef<{ x: number; y: number }>({ x: 0, y: 0 })
+  const lastLogTimeRef = useRef<number>(0) // Separate throttling for logging
+  const cardRef = useRef<HTMLDivElement>(null) // Reference to card element
 
-        // Calculate drag offset from card center on first touch
-        if (first && cardRef.current) {
-          const cardRect = cardRef.current.getBoundingClientRect()
-          const cardWidth = cardRect.width
-          const cardHeight = cardRect.height
+  const handlePointerDown = (e: React.PointerEvent) => {
+    setIsDragging(true)
+    setZIndex(1000) // Bring to front
+    setDragSpeed(0)
 
-          // xy is in viewport coordinates, convert to position relative to card
-          const clickRelativeToCard = {
-            x: xy[0] - cardRect.left,
-            y: xy[1] - cardRect.top,
-          }
+    // Capture the pointer
+    e.currentTarget.setPointerCapture(e.pointerId)
 
-          // Calculate offset from card center
-          const cardCenterX = cardWidth / 2
-          const cardCenterY = cardHeight / 2
-          const offsetX = clickRelativeToCard.x - cardCenterX
-          const offsetY = clickRelativeToCard.y - cardCenterY
-
-          dragOffsetRef.current = { x: offsetX, y: offsetY }
-
-          // Convert offset to transform-origin (50% + offset as percentage of card size)
-          const originX = 50 + (offsetX / cardWidth) * 100
-          const originY = 50 + (offsetY / cardHeight) * 100
-          const transformOriginValue = `${originX}% ${originY}%`
-
-          console.log(
-            `Drag start: click at (${clickRelativeToCard.x.toFixed(0)}, ${clickRelativeToCard.y.toFixed(0)}) in card, offset from center: (${offsetX.toFixed(0)}, ${offsetY.toFixed(0)}), origin: ${transformOriginValue}`
-          )
-
-          setTransformOrigin(transformOriginValue)
-          velocityHistoryRef.current = []
-        }
-
-        // Smooth velocity by averaging last 3 frames
-        velocityHistoryRef.current.push({ vx, vy })
-        if (velocityHistoryRef.current.length > 3) {
-          velocityHistoryRef.current.shift()
-        }
-
-        const avgVx =
-          velocityHistoryRef.current.reduce((sum, v) => sum + v.vx, 0) /
-          velocityHistoryRef.current.length
-        const avgVy =
-          velocityHistoryRef.current.reduce((sum, v) => sum + v.vy, 0) /
-          velocityHistoryRef.current.length
-
-        // Calculate rotation based on smoothed velocity and drag offset
-        const velocityAngle = Math.atan2(avgVy, avgVx) * (180 / Math.PI)
-        const offsetAngle =
-          Math.atan2(dragOffsetRef.current.y, dragOffsetRef.current.x) * (180 / Math.PI)
-
-        // Card rotates to align with movement direction, offset by where we're grabbing
-        const targetRotation = velocityAngle - offsetAngle + 90
-
-        const speed = Math.sqrt(avgVx * avgVx + avgVy * avgVy)
-
-        // Store smoothed velocity for throw
-        lastVelocityRef.current = { vx: avgVx, vy: avgVy }
-
-        const finalRotation = speed > 0.01 ? targetRotation : currentPositionRef.current.rotation
-
-        api.start({
-          x: currentPositionRef.current.x + mx,
-          y: currentPositionRef.current.y + my,
-          scale: 1.1,
-          rotation: finalRotation,
-          immediate: (key) => key !== 'rotation', // Position immediate, rotation smooth
-          config: { tension: 200, friction: 30 }, // Smoother rotation spring
-        })
-      } else {
-        // On release, reset transform origin to center
-        setTransformOrigin('center center')
-
-        // On release, apply momentum with decay physics
-        const throwVelocityX = lastVelocityRef.current.vx * 1000
-        const throwVelocityY = lastVelocityRef.current.vy * 1000
-
-        // Calculate final rotation based on throw direction
-        const throwAngle = Math.atan2(throwVelocityY, throwVelocityX) * (180 / Math.PI)
-
-        api.start({
-          x: {
-            from: currentPositionRef.current.x + mx,
-            velocity: throwVelocityX,
-            decay: true,
-          },
-          y: {
-            from: currentPositionRef.current.y + my,
-            velocity: throwVelocityY,
-            decay: true,
-          },
-          scale: 1,
-          rotation: throwAngle + 90, // Card aligns with throw direction
-          config: config.wobbly,
-          onChange: (result) => {
-            // Update current position as card settles
-            if (result.value.x !== undefined) {
-              currentPositionRef.current.x = result.value.x
-            }
-            if (result.value.y !== undefined) {
-              currentPositionRef.current.y = result.value.y
-            }
-            if (result.value.rotation !== undefined) {
-              currentPositionRef.current.rotation = result.value.rotation
-            }
-          },
-        })
-      }
-    },
-    {
-      // Prevent scrolling when dragging
-      preventDefault: true,
-      filterTaps: true,
+    // Record where the drag started (pointer position and card position)
+    dragStartRef.current = {
+      x: e.clientX,
+      y: e.clientY,
+      cardX: position.x,
+      cardY: position.y,
     }
-  )
+
+    // Calculate grab offset from card center IN LOCAL COORDINATES (unrotated)
+    if (cardRef.current) {
+      const rect = cardRef.current.getBoundingClientRect()
+      const cardCenterX = rect.left + rect.width / 2
+      const cardCenterY = rect.top + rect.height / 2
+
+      // Screen-space offset from center
+      const screenOffsetX = e.clientX - cardCenterX
+      const screenOffsetY = e.clientY - cardCenterY
+
+      // Convert to local coordinates by rotating by -rotation
+      const currentRotationRad = (rotation * Math.PI) / 180
+      const cosRot = Math.cos(-currentRotationRad)
+      const sinRot = Math.sin(-currentRotationRad)
+
+      grabOffsetRef.current = {
+        x: screenOffsetX * cosRot - screenOffsetY * sinRot,
+        y: screenOffsetX * sinRot + screenOffsetY * cosRot,
+      }
+      console.log(
+        `[GrabPoint] Grabbed at local offset: (${grabOffsetRef.current.x.toFixed(0)}, ${grabOffsetRef.current.y.toFixed(0)})px (screen offset: ${screenOffsetX.toFixed(0)}, ${screenOffsetY.toFixed(0)}px, rotation: ${rotation.toFixed(1)}°)`
+      )
+    }
+
+    // Store the current rotation as the base for this drag
+    baseRotationRef.current = rotation
+
+    // Initialize velocity tracking
+    const now = Date.now()
+    lastMoveTimeRef.current = now
+    lastMovePositionRef.current = { x: e.clientX, y: e.clientY }
+    lastLogTimeRef.current = now
+
+    console.log('[Shadow] Drag started, speed reset to 0')
+  }
+
+  const handlePointerMove = (e: React.PointerEvent) => {
+    if (!isDragging || !dragStartRef.current) return
+
+    // Calculate how far the pointer has moved since drag started
+    const deltaX = e.clientX - dragStartRef.current.x
+    const deltaY = e.clientY - dragStartRef.current.y
+
+    // Calculate velocity for dynamic shadow
+    const now = Date.now()
+    const timeDelta = now - lastMoveTimeRef.current
+
+    if (timeDelta > 0) {
+      // Distance moved since last frame
+      const distX = e.clientX - lastMovePositionRef.current.x
+      const distY = e.clientY - lastMovePositionRef.current.y
+      const distance = Math.sqrt(distX * distX + distY * distY)
+
+      // Speed in pixels per millisecond, then convert to reasonable scale
+      const speed = distance / timeDelta
+      const scaledSpeed = Math.min(speed * 100, 100) // Cap at 100 for reasonable shadow size
+
+      setDragSpeed(scaledSpeed)
+
+      // Log occasionally (every ~200ms) to avoid console spam
+      const timeSinceLastLog = now - lastLogTimeRef.current
+      if (timeSinceLastLog > 200) {
+        console.log(
+          `[Shadow] Speed: ${scaledSpeed.toFixed(1)}, distance: ${distance.toFixed(0)}px, timeDelta: ${timeDelta}ms`
+        )
+        lastLogTimeRef.current = now
+      }
+
+      lastMoveTimeRef.current = now
+      lastMovePositionRef.current = { x: e.clientX, y: e.clientY }
+    }
+
+    // Calculate rotation based on grab point physics
+    // Cross product of grab offset and drag direction determines rotation
+    // If grabbed on left and dragged right → clockwise rotation
+    // If grabbed on right and dragged left → counter-clockwise rotation
+    const crossProduct = grabOffsetRef.current.x * deltaY - grabOffsetRef.current.y * deltaX
+    const rotationInfluence = crossProduct / 500 // Reduced scale factor for more visible rotation
+    const newRotation = baseRotationRef.current + rotationInfluence
+
+    // Clamp rotation to prevent excessive spinning
+    const clampedRotation = Math.max(-45, Math.min(45, newRotation))
+    setRotation(clampedRotation)
+
+    // Log rotation changes occasionally (same throttle as shadow logging)
+    const timeSinceLastLog = now - lastLogTimeRef.current
+    if (timeSinceLastLog > 200) {
+      console.log(
+        `[GrabPoint] Rotation: ${clampedRotation.toFixed(1)}° (influence: ${rotationInfluence.toFixed(1)}°, cross: ${crossProduct.toFixed(0)})`
+      )
+    }
+
+    // Update card position - keep grab point under cursor while rotating
+    // Calculate the rotated grab offset
+    const rotationRad = (clampedRotation * Math.PI) / 180
+    const cosRot = Math.cos(rotationRad)
+    const sinRot = Math.sin(rotationRad)
+
+    // Rotate the grab offset by the current rotation angle
+    const rotatedGrabX = grabOffsetRef.current.x * cosRot - grabOffsetRef.current.y * sinRot
+    const rotatedGrabY = grabOffsetRef.current.x * sinRot + grabOffsetRef.current.y * cosRot
+
+    // Get container bounds for coordinate conversion
+    if (!containerRef.current || !cardRef.current) {
+      // Fallback to simple delta if refs not ready
+      setPosition({
+        x: dragStartRef.current.cardX + deltaX,
+        y: dragStartRef.current.cardY + deltaY,
+      })
+      return
+    }
+
+    const containerRect = containerRef.current.getBoundingClientRect()
+    const cardRect = cardRef.current.getBoundingClientRect()
+
+    // Current cursor position in viewport space
+    const cursorViewportX = e.clientX
+    const cursorViewportY = e.clientY
+
+    // Card center should be at: cursor - rotated grab offset (viewport space)
+    const cardCenterViewportX = cursorViewportX - rotatedGrabX
+    const cardCenterViewportY = cursorViewportY - rotatedGrabY
+
+    // Convert card center from viewport space to container space
+    const cardCenterContainerX = cardCenterViewportX - containerRect.left
+    const cardCenterContainerY = cardCenterViewportY - containerRect.top
+
+    // position.x/y represents translate() which positions the top-left corner
+    // So we need: top-left = center - (width/2, height/2)
+    setPosition({
+      x: cardCenterContainerX - cardRect.width / 2,
+      y: cardCenterContainerY - cardRect.height / 2,
+    })
+  }
+
+  const handlePointerUp = (e: React.PointerEvent) => {
+    setIsDragging(false)
+    dragStartRef.current = null
+
+    console.log('[Shadow] Drag released, speed decaying to 0')
+    console.log(
+      `[GrabPoint] Final rotation: ${rotation.toFixed(1)}° (base was ${baseRotationRef.current.toFixed(1)}°)`
+    )
+
+    // Gradually decay speed back to 0 for smooth shadow transition
+    const decayInterval = setInterval(() => {
+      setDragSpeed((prev) => {
+        const newSpeed = prev * 0.8 // Decay by 20% each frame
+        if (newSpeed < 1) {
+          clearInterval(decayInterval)
+          return 0
+        }
+        return newSpeed
+      })
+    }, 50) // Update every 50ms
+
+    // Release the pointer capture
+    e.currentTarget.releasePointerCapture(e.pointerId)
+  }
+
+  // Calculate dynamic shadow based on drag speed
+  // Base shadow: 0 8px 24px rgba(0, 0, 0, 0.3)
+  // Fast drag: 0 32px 64px rgba(0, 0, 0, 0.6)
+  const shadowY = 8 + (dragSpeed / 100) * 24 // 8px to 32px
+  const shadowBlur = 24 + (dragSpeed / 100) * 40 // 24px to 64px
+  const shadowOpacity = 0.3 + (dragSpeed / 100) * 0.3 // 0.3 to 0.6
+  const boxShadow = `0 ${shadowY}px ${shadowBlur}px rgba(0, 0, 0, ${shadowOpacity})`
 
   return (
-    <animated.div
+    <div
       ref={cardRef}
-      {...bind()}
+      onPointerDown={handlePointerDown}
+      onPointerMove={handlePointerMove}
+      onPointerUp={handlePointerUp}
       style={{
         position: 'absolute',
         left: 0,
         top: 0,
-        transform: to(
-          [x, y, rotation, scale],
-          (x, y, r, s) => `translate(${x}px, ${y}px) rotate(${r}deg) scale(${s})`
-        ),
-        transformOrigin,
+        transform: `translate(${position.x}px, ${position.y}px) rotate(${rotation}deg) scale(${isDragging ? 1.05 : 1})`,
         zIndex,
         touchAction: 'none',
-        cursor: 'grab',
+        cursor: isDragging ? 'grabbing' : 'grab',
+        transition: isDragging ? 'none' : 'transform 0.2s ease-out',
       }}
       className={css({
         userSelect: 'none',
-        _active: {
-          cursor: 'grabbing',
-        },
       })}
     >
       <div
+        style={{
+          boxShadow, // Dynamic shadow based on drag speed
+        }}
         className={css({
           bg: 'white',
           rounded: 'lg',
           p: '4',
-          boxShadow: '0 8px 24px rgba(0, 0, 0, 0.3)',
           display: 'flex',
           flexDirection: 'column',
           alignItems: 'center',
           gap: '2',
           minW: '120px',
           border: '2px solid rgba(0, 0, 0, 0.1)',
-          transition: 'box-shadow 0.2s',
-          _hover: {
-            boxShadow: '0 12px 32px rgba(0, 0, 0, 0.4)',
-          },
+          transition: 'box-shadow 0.1s', // Quick transition for responsive feel
         })}
       >
         {/* Abacus visualization */}
@@ -288,7 +339,7 @@ function DraggableCard({ card }: DraggableCardProps) {
             transformOrigin: 'center',
           })}
         >
-          <AbacusReact value={card.number} columns={3} beadShape="circle" />
+          <AbacusReact value={card.number} columns={3} beadShape={appConfig.beadShape} />
         </div>
 
         {/* Number display */}
@@ -303,6 +354,6 @@ function DraggableCard({ card }: DraggableCardProps) {
           {card.number}
         </div>
       </div>
-    </animated.div>
+    </div>
   )
 }

apps/web/src/components/LevelSliderDisplay.tsx

@@ -412,8 +412,9 @@ export function LevelSliderDisplay({
                   ? 'violet.500'
                   : 'amber.500',
           rounded: 'xl',
-          p: { base: '6', md: '8' },
+          p: { base: '4', md: '8' },
           height: { base: 'auto', md: '700px' },
+          maxHeight: { base: '500px', md: 'none' },
           display: 'flex',
           flexDirection: 'column',
         })}
@@ -448,7 +449,7 @@ export function LevelSliderDisplay({
                     key={index}
                     onClick={() => setCurrentIndex(index)}
                     className={css({
-                      fontSize: '4xl',
+                      fontSize: { base: '2xl', sm: '3xl', md: '4xl' },
                       opacity: index === currentIndex ? '1' : '0.3',
                       transition: 'all 0.2s',
                       cursor: 'pointer',
@@ -500,8 +501,8 @@ export function LevelSliderDisplay({
                   alignItems: 'center',
                   justifyContent: 'center',
                   position: 'relative',
-                  w: '180px',
-                  h: '128px',
+                  w: { base: '120px', md: '180px' },
+                  h: { base: '96px', md: '128px' },
                   bg: 'transparent',
                   cursor: 'grab',
                   transition: 'transform 0.15s ease-out, left 0.3s ease-out',
@@ -514,7 +515,12 @@ export function LevelSliderDisplay({
                   _active: { cursor: 'grabbing' },
                 })}
               >
-                <div className={css({ opacity: 0.75 })}>
+                <div
+                  className={css({
+                    opacity: 0.75,
+                    transform: { base: 'scale(0.75)', md: 'scale(1)' },
+                  })}
+                >
                   <StandaloneBead
                     size={128}
                     color={currentLevel.color === 'violet' ? '#8b5cf6' : '#22c55e'}
@@ -607,14 +613,16 @@ export function LevelSliderDisplay({
         <div
           className={css({
             display: 'flex',
+            flexDirection: { base: 'column', lg: 'row' },
             gap: '4',
-            p: '6',
+            p: { base: '4', md: '6' },
             bg: 'rgba(0, 0, 0, 0.3)',
             rounded: 'lg',
             border: '1px solid',
             borderColor: 'gray.700',
             overflow: 'hidden',
             flex: 1,
+            minH: 0, // Allow flex shrinking
           })}
         >
           {/* Level Details (only for Kyu levels) */}
@@ -633,12 +641,14 @@ export function LevelSliderDisplay({
                 <div
                   className={css({
                     flex: '0 0 auto',
-                    display: 'grid',
+                    display: { base: 'none', lg: 'grid' },
                     gridTemplateColumns: 'repeat(2, 1fr)',
                     gap: '2',
                     p: '2',
+                    w: '100%',
                     maxW: '400px',
                     alignContent: 'center',
+                    justifyItems: 'center',
                   })}
                 >
                   {sections.map((section, idx) => {
@@ -666,8 +676,10 @@ export function LevelSliderDisplay({
                           justifyContent: 'center',
                           gap: '1.5',
                           opacity: hasData ? 1 : 0.3,
-                          width: '170px',
-                          height: '150px',
+                          w: { base: '100%', sm: 'auto' },
+                          minW: { sm: '140px' },
+                          maxW: { base: '170px', sm: '170px' },
+                          minH: '150px',
                           _hover: hasData
                             ? {
                                 borderColor: 'gray.500',
@@ -733,13 +745,18 @@ export function LevelSliderDisplay({
               ) : null
             })()}
 
-          {/* Abacus (right-aligned for Kyu, centered for Dan) */}
+          {/* Abacus (centered on mobile, right-aligned for Kyu on desktop, centered for Dan) */}
           <div
             className={css({
               display: 'flex',
-              justifyContent: currentLevel.type === 'kyu' ? 'flex-end' : 'center',
+              justifyContent:
+                currentLevel.type === 'kyu' ? { base: 'center', lg: 'flex-end' } : 'center',
               alignItems: 'center',
               flex: 1,
+              overflowX: 'auto',
+              overflowY: 'hidden',
+              minW: 0, // Allow flex shrinking
+              minH: 0, // Allow flex shrinking
             })}
           >
             <animated.div

package.json

@@ -1,6 +1,6 @@
 {
   "name": "soroban-monorepo",
-  "version": "4.57.2",
+  "version": "4.67.3",
   "private": true,
   "description": "Beautiful Soroban Flashcard Generator - Monorepo",
   "workspaces": [