feat: improve worksheet preview placeholder with cartoonish grid layout

Enhanced PagePlaceholder component to show a visual preview of the actual
worksheet layout:

Layout Matching:
- Calculate rows per page correctly (problemsPerPage / cols)
- Match exact page dimensions (816×1056 portrait, 1056×816 landscape)
- Display cartoonish grid with correct rows × cols matching worksheet

Visual Design:
- Header bars mimicking name/date fields
- Problem cells with mini bars representing:
  - Problem number (top-left)
  - Two operands (right-aligned)
  - Answer line separator
- Semi-transparent grid overlay with centered info badge

Unified Loading States:
- Single component handles both idle and loading states
- Idle: "Scroll to load" with slower pulse
- Loading: Spinning hourglass with "Loading page X..."
- Both show same grid layout for consistency

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/web/src/app/create/worksheets/components/PagePlaceholder.tsx

@@ -6,40 +6,206 @@ import { useTheme } from '@/contexts/ThemeContext'
 interface PagePlaceholderProps {
   pageNumber: number
   orientation?: 'portrait' | 'landscape'
+  rows?: number
+  cols?: number
+  loading?: boolean
 }
 
-export function PagePlaceholder({ pageNumber, orientation = 'portrait' }: PagePlaceholderProps) {
+export function PagePlaceholder({
+  pageNumber,
+  orientation = 'portrait',
+  rows = 5,
+  cols = 4,
+  loading = false,
+}: PagePlaceholderProps) {
   const { resolvedTheme } = useTheme()
   const isDark = resolvedTheme === 'dark'
 
-  // Match the aspect ratio of actual worksheet pages
+  // Calculate exact pixel dimensions based on page size
-  // Portrait: 8.5" × 11" (aspect ratio 1:1.294)
+  // Portrait: 8.5" × 11" at 96 DPI = 816px × 1056px
-  // Landscape: 11" × 8.5" (aspect ratio 1.294:1)
+  // Landscape: 11" × 8.5" at 96 DPI = 1056px × 816px
-  const aspectRatio = orientation === 'portrait' ? 11 / 8.5 : 8.5 / 11
+  // Scale down to fit typical viewport (maxWidth: 100%)
+  const width = orientation === 'portrait' ? 816 : 1056
+  const height = orientation === 'portrait' ? 1056 : 816
 
   return (
     <div
       data-component="page-placeholder"
       data-page-number={pageNumber}
+      style={{
+        maxWidth: '100%',
+        width: `${width}px`,
+        height: `${height}px`,
+      }}
       className={css({
         bg: isDark ? 'gray.800' : 'gray.100',
         border: '2px dashed',
         borderColor: isDark ? 'gray.600' : 'gray.300',
         rounded: 'lg',
-        width: '100%',
+        animation: loading ? 'pulse 1.5s ease-in-out infinite' : 'pulse 2s ease-in-out infinite',
-        aspectRatio: `1 / ${aspectRatio}`,
+        position: 'relative',
         display: 'flex',
         flexDirection: 'column',
-        alignItems: 'center',
+        padding: '12',
-        justifyContent: 'center',
+      })}
-        gap: '4',
+    >
-        animation: 'pulse 2s ease-in-out infinite',
+      {/* Header area (mimics worksheet header with name/date) */}
+      <div
+        className={css({
+          display: 'flex',
+          justifyContent: 'space-between',
+          mb: '8',
+          opacity: 0.3,
         })}
       >
         <div
           className={css({
-          fontSize: '4xl',
+            width: '30%',
-          color: isDark ? 'gray.600' : 'gray.400',
+            height: '6',
+            bg: isDark ? 'gray.600' : 'gray.400',
+            rounded: 'sm',
+          })}
+        />
+        <div
+          className={css({
+            width: '25%',
+            height: '6',
+            bg: isDark ? 'gray.600' : 'gray.400',
+            rounded: 'sm',
+          })}
+        />
+      </div>
+
+      {/* Problem grid - cartoonish representation */}
+      <div
+        data-element="problem-grid-preview"
+        className={css({
+          flex: 1,
+          display: 'flex',
+          flexDirection: 'column',
+          gap: '3',
+          opacity: 0.3,
+        })}
+      >
+        {Array.from({ length: rows }).map((_, rowIndex) => (
+          <div
+            key={rowIndex}
+            className={css({
+              display: 'flex',
+              gap: '3',
+              flex: 1,
+            })}
+          >
+            {Array.from({ length: cols }).map((_, colIndex) => (
+              <div
+                key={colIndex}
+                className={css({
+                  flex: 1,
+                  bg: isDark ? 'gray.700' : 'gray.300',
+                  border: '1px solid',
+                  borderColor: isDark ? 'gray.600' : 'gray.400',
+                  rounded: 'md',
+                  display: 'flex',
+                  flexDirection: 'column',
+                  padding: '2',
+                  gap: '1',
+                })}
+              >
+                {/* Problem number */}
+                <div
+                  className={css({
+                    width: '20%',
+                    height: '2',
+                    bg: isDark ? 'gray.600' : 'gray.500',
+                    rounded: 'xs',
+                  })}
+                />
+                {/* Top operand */}
+                <div
+                  className={css({
+                    width: '60%',
+                    height: '3',
+                    bg: isDark ? 'gray.600' : 'gray.500',
+                    rounded: 'xs',
+                    alignSelf: 'flex-end',
+                  })}
+                />
+                {/* Bottom operand */}
+                <div
+                  className={css({
+                    width: '60%',
+                    height: '3',
+                    bg: isDark ? 'gray.600' : 'gray.500',
+                    rounded: 'xs',
+                    alignSelf: 'flex-end',
+                  })}
+                />
+                {/* Answer line */}
+                <div
+                  className={css({
+                    width: '60%',
+                    height: '1px',
+                    bg: isDark ? 'gray.600' : 'gray.500',
+                    alignSelf: 'flex-end',
+                  })}
+                />
+              </div>
+            ))}
+          </div>
+        ))}
+      </div>
+
+      {/* Page info overlay */}
+      <div
+        className={css({
+          position: 'absolute',
+          top: '50%',
+          left: '50%',
+          transform: 'translate(-50%, -50%)',
+          display: 'flex',
+          flexDirection: 'column',
+          alignItems: 'center',
+          gap: '2',
+          zIndex: 1,
+          bg: isDark ? 'rgba(31, 41, 55, 0.95)' : 'rgba(243, 244, 246, 0.95)',
+          px: '6',
+          py: '4',
+          rounded: 'lg',
+          border: '2px solid',
+          borderColor: isDark ? 'gray.600' : 'gray.400',
+          backdropFilter: 'blur(4px)',
+        })}
+      >
+        {loading ? (
+          <>
+            <div
+              className={css({
+                fontSize: '3xl',
+                color: isDark ? 'gray.500' : 'gray.400',
+                animation: 'spin',
+                animationDuration: '1s',
+                animationTimingFunction: 'linear',
+                animationIterationCount: 'infinite',
+              })}
+            >
+              ⏳
+            </div>
+            <div
+              className={css({
+                fontSize: 'lg',
+                fontWeight: 'semibold',
+                color: isDark ? 'gray.300' : 'gray.700',
+              })}
+            >
+              Loading page {pageNumber}...
+            </div>
+          </>
+        ) : (
+          <>
+            <div
+              className={css({
+                fontSize: '3xl',
+                color: isDark ? 'gray.500' : 'gray.400',
               })}
             >
               📄
@@ -48,7 +214,7 @@ export function PagePlaceholder({ pageNumber, orientation = 'portrait' }: PagePl
               className={css({
                 fontSize: 'lg',
                 fontWeight: 'semibold',
-          color: isDark ? 'gray.500' : 'gray.500',
+                color: isDark ? 'gray.300' : 'gray.700',
               })}
             >
               Page {pageNumber}
@@ -56,10 +222,13 @@ export function PagePlaceholder({ pageNumber, orientation = 'portrait' }: PagePl
             <div
               className={css({
                 fontSize: 'sm',
-          color: isDark ? 'gray.600' : 'gray.400',
+                color: isDark ? 'gray.400' : 'gray.600',
               })}
             >
-        Loading...
+              Scroll to load
+            </div>
+          </>
+        )}
       </div>
     </div>
   )

apps/web/src/app/create/worksheets/components/WorksheetPreview.tsx

@@ -436,39 +436,14 @@ function PreviewContent({ formState, initialData, isScrolling = false }: Workshe
                   })}
                   dangerouslySetInnerHTML={{ __html: page }}
                 />
-              ) : isFetching ? (
-                <div
-                  data-element="page-loading"
-                  className={css({
-                    display: 'flex',
-                    flexDirection: 'column',
-                    alignItems: 'center',
-                    gap: '4',
-                    p: '8',
-                  })}
-                >
-                  <div
-                    className={css({
-                      fontSize: '2xl',
-                      animation: 'spin',
-                      animationDuration: '1s',
-                      animationTimingFunction: 'linear',
-                      animationIterationCount: 'infinite',
-                    })}
-                  >
-                    ⏳
-                  </div>
-                  <p
-                    className={css({
-                      fontSize: 'sm',
-                      color: isDark ? 'gray.400' : 'gray.600',
-                    })}
-                  >
-                    Loading page {index + 1}...
-                  </p>
-                </div>
               ) : (
-                <PagePlaceholder pageNumber={index + 1} orientation={formState.orientation} />
+                <PagePlaceholder
+                  pageNumber={index + 1}
+                  orientation={formState.orientation}
+                  rows={Math.ceil((formState.problemsPerPage ?? 20) / (formState.cols ?? 5))}
+                  cols={formState.cols}
+                  loading={isFetching}
+                />
               )}
             </div>
           )