fix(compare): keep the add-school sheet above the on-screen keyboard

The bottom-sheet overlay was position:fixed inset:0, sized to the LAYOUT
viewport, so when the mobile keyboard opened it kept full height: the
sheet (anchored to the overlay's bottom) and the lower half of the dim
backdrop sat behind the keyboard, hiding the search input and results.

Track window.visualViewport (height + offsetTop) while the modal is open
and pin the overlay to the visible region, so backdrop and sheet stay
above the keyboard. Size the sheet against the overlay (max-height:100%,
min-height:min(55vh,100%)) instead of vh, and drop the results list's own
inner scroll on mobile so the sheet is a single scroll area.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0146VHeLAWjDVE2B5uU67jCB

nextjs-app/components/ComparisonChart.module.css

@@ -1,16 +1,23 @@
-/* Chart wrapper: chips (mobile) above, canvas filling the rest of the
-   parent .chartContainer, whose fixed height drives Chart.js sizing via
-   maintainAspectRatio: false. */
+/* Chart wrapper: chips (mobile) above, then the canvas, then the gap note.
+   The canvas has its OWN definite height (Chart.js needs one for
+   maintainAspectRatio: false); the chips and the note flow at their natural
+   size around it rather than competing with it for a fixed outer height —
+   so a longer note (e.g. the KS4 gap caption) or a two-row chip legend can
+   never squash the chart. */
 .wrapper {
     display: flex;
     flex-direction: column;
-    height: 100%;
 }
 
 .canvasBox {
     position: relative;
-    flex: 1 1 auto;
-    min-height: 0;
+    height: 380px;
+}
+
+@media (max-width: 640px) {
+    .canvasBox {
+        height: 280px;
+    }
 }
 
 /* School chips: mobile-only legend + tap-to-focus control. Desktop keeps

nextjs-app/components/Modal.module.css

@@ -123,7 +123,13 @@
   .modal {
     width: 100%;
     max-width: 100%;
-    max-height: 95vh;
+    /* Bottom sheet sized against the overlay (which tracks the visual
+       viewport), NOT vh: when the keyboard is open the overlay is short, so
+       max-height:100% keeps the whole sheet — input and results — above the
+       keyboard. min-height gives a comfortable default without a tiny stub,
+       but is capped at 100% so it never exceeds the visible area. */
+    min-height: min(55vh, 100%);
+    max-height: 100%;
     border-bottom-left-radius: 0;
     border-bottom-right-radius: 0;
     animation: slideUp 0.3s ease;

nextjs-app/components/Modal.tsx

@@ -5,7 +5,7 @@
 
 'use client';
 
-import { useEffect, useCallback } from 'react';
+import { useEffect, useCallback, useRef } from 'react';
 import { createPortal } from 'react-dom';
 import styles from './Modal.module.css';
 
@@ -18,6 +18,8 @@ interface ModalProps {
 }
 
 export function Modal({ isOpen, onClose, children, title, size = 'medium' }: ModalProps) {
+  const overlayRef = useRef<HTMLDivElement>(null);
+
   const handleEscape = useCallback((e: KeyboardEvent) => {
     if (e.key === 'Escape') {
       onClose();
@@ -39,6 +41,32 @@ export function Modal({ isOpen, onClose, children, title, size = 'medium' }: Mod
     };
   }, [isOpen, handleEscape]);
 
+  // Pin the overlay to the VISUAL viewport, not the layout viewport. On mobile
+  // the on-screen keyboard shrinks the visual viewport but not the layout one,
+  // so a `position: fixed; inset: 0` overlay keeps full height — leaving the
+  // bottom-anchored sheet (and the dim backdrop's lower half) hidden behind
+  // the keyboard. Tracking visualViewport.height/offsetTop keeps the whole
+  // overlay — backdrop and sheet — inside the visible area, above the keyboard.
+  useEffect(() => {
+    if (!isOpen) return;
+    const vv = typeof window !== 'undefined' ? window.visualViewport : null;
+    const el = overlayRef.current;
+    if (!vv || !el) return;
+
+    const sync = () => {
+      el.style.top = `${vv.offsetTop}px`;
+      el.style.height = `${vv.height}px`;
+      el.style.bottom = 'auto';
+    };
+    sync();
+    vv.addEventListener('resize', sync);
+    vv.addEventListener('scroll', sync);
+    return () => {
+      vv.removeEventListener('resize', sync);
+      vv.removeEventListener('scroll', sync);
+    };
+  }, [isOpen]);
+
   if (!isOpen || typeof window === 'undefined') return null;
 
   const handleOverlayClick = (e: React.MouseEvent) => {
@@ -48,7 +76,7 @@ export function Modal({ isOpen, onClose, children, title, size = 'medium' }: Mod
   };
 
   return createPortal(
-    <div className={styles.overlay} onClick={handleOverlayClick}>
+    <div ref={overlayRef} className={styles.overlay} onClick={handleOverlayClick}>
       <div className={`${styles.modal} ${styles[size]}`}>
         <div className={styles.header}>
           {title && <h2 className={styles.title}>{title}</h2>}

nextjs-app/components/SchoolSearchModal.module.css

@@ -2,14 +2,6 @@
   padding: 1.5rem;
 }
 
-.title {
-  font-size: 1.5rem;
-  font-weight: 700;
-  color: var(--text-primary, #1a1612);
-  margin-bottom: 1.5rem;
-  font-family: var(--font-playfair), 'Playfair Display', serif;
-}
-
 .warning {
   background: var(--accent-gold-bg);
   border: 1px solid var(--accent-gold, #c9a227);
@@ -119,12 +111,16 @@
   font-size: 1rem;
   font-weight: 600;
   color: var(--text-primary, #1a1612);
-  margin-bottom: 0.5rem;
+  margin-bottom: 0.25rem;
   white-space: nowrap;
   overflow: hidden;
   text-overflow: ellipsis;
 }
 
+.resultButton {
+  flex: 0 0 auto;
+}
+
 .schoolMeta {
   display: flex;
   gap: 1rem;
@@ -159,21 +155,30 @@
     padding: 1rem;
   }
 
-  .title {
-    font-size: 1.25rem;
+  /* One scroll container on mobile: the modal content itself scrolls, so the
+     results list must not add its own inner scroll (double scrollbars, and
+     the input would be trapped above a short 400px window when the keyboard
+     shrinks the sheet). */
+  .results {
+    max-height: none;
+    overflow: visible;
   }
 
+  /* Compact stacked card: name + meta, then a full-width action so the tap
+     target is obvious and the card doesn't waste vertical space. */
   .resultItem {
     flex-direction: column;
     align-items: stretch;
+    gap: 0.625rem;
+    padding: 0.875rem;
   }
 
-  .addButton {
+  .resultButton {
     width: 100%;
   }
 
   .schoolMeta {
-    flex-direction: column;
-    gap: 0.25rem;
+    flex-wrap: wrap;
+    gap: 0.25rem 1rem;
   }
 }

nextjs-app/components/SchoolSearchModal.tsx

@@ -81,10 +81,8 @@ export function SchoolSearchModal({ isOpen, onClose }: SchoolSearchModalProps) {
   };
 
   return (
-    <Modal isOpen={isOpen} onClose={handleClose}>
+    <Modal isOpen={isOpen} onClose={handleClose} title="Add School to Comparison">
       <div className={styles.modalContent}>
-        <h2 className={styles.title}>Add School to Comparison</h2>
-
         {!canAddMore && (
           <div className={styles.warning}>
             Maximum 5 schools can be compared. Remove a school to add another.
@@ -129,9 +127,9 @@ export function SchoolSearchModal({ isOpen, onClose }: SchoolSearchModalProps) {
                 <button
                   onClick={() => handleAddSchool(school)}
                   disabled={alreadySelected || !canAddMore}
-                  className={
+                  className={`${styles.resultButton} ${
                     alreadySelected ? "btn btn-active" : "btn btn-secondary"
-                  }
+                  }`}
                 >
                   {alreadySelected ? "✓ Comparing" : "+ Compare"}
                 </button>

nextjs-app/components/compare/TrendsExplorer.module.css

@@ -60,18 +60,10 @@
   margin: 0 0 1rem;
 }
 
-/* ComparisonChart runs Chart.js with maintainAspectRatio:false, so it fills
-   its container's height — which must be *definite*. A min-height alone does
-   not resolve the chart wrapper's height:100%, leaving Chart.js to fall back
-   to its ~150px default (a squashed sliver). Give it a real height. */
+/* ComparisonChart owns its own canvas height now (a definite px value per
+   breakpoint), with the mobile chip legend above and the gap note below it
+   flowing at natural size. This box therefore only needs to not constrain
+   that height — no fixed height, or the note would again eat the plot. */
 .chartBox {
-  height: 420px;
-}
-
-@media (max-width: 640px) {
-  /* Taller on mobile: the mobile-only school chips sit above the canvas and
-     wrap to two rows for 3+ schools, so the plot keeps a usable height. */
-  .chartBox {
-    height: 360px;
-  }
+  min-height: 0;
 }