feat(nav): mobile bottom tab bar and ≥44px logo tap target

MOB-01: At ≤640px the top inline nav is hidden and replaced by a
fixed bottom tab bar (Search / Compare / Rankings / Admissions) with
icon + label, 56px tap targets, env(safe-area-inset-bottom) padding,
and the Compare count rendered as a badge on the icon. Eliminates
horizontal page overflow on every route (docW was 401–429 at vw 390;
now docW === vw).

MOB-02: Logo link gains a padded hit area so the touch target is
≥44×44 (was 36×36), without resizing the visual mark.

ComparisonToast lifted above the new bottom bar on mobile so the two
do not stack on top of each other. body gets a bottom padding equal
to the bar height + safe-area inset so page content is never hidden.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

nextjs-app/app/globals.css

@@ -95,6 +95,13 @@ body {
     min-height: 100vh;
 }
 
+/* Reserve space for the fixed mobile bottom tab bar (56px + safe-area inset). */
+@media (max-width: 640px) {
+    body {
+        padding-bottom: calc(56px + env(safe-area-inset-bottom, 0px));
+    }
+}
+
 /* Skip link — visible only on focus for keyboard users */
 .skip-link {
     position: absolute;

nextjs-app/components/ComparisonToast.module.css

@@ -169,8 +169,9 @@
 
 @media (max-width: 640px) {
   .toastContainer {
-    bottom: 1.5rem;
-    width: calc(100% - 3rem);
+    /* Sit above the fixed bottom tab bar (56px + safe-area inset) */
+    bottom: calc(56px + env(safe-area-inset-bottom, 0px) + 0.75rem);
+    width: calc(100% - 2rem);
   }
 
   .toastContent {

nextjs-app/components/Navigation.module.css

@@ -21,11 +21,15 @@
   display: flex;
   align-items: center;
   gap: 0.75rem;
+  /* Padded hit area so the logo link is ≥44×44 on touch */
+  margin: -0.375rem -0.5rem;
+  padding: 0.375rem 0.5rem;
   text-decoration: none;
   color: var(--text-primary, #1a1612);
   font-size: 1.25rem;
   font-weight: 700;
   transition: color 0.2s ease;
+  -webkit-tap-highlight-color: transparent;
 }
 
 .logo:hover {
@@ -33,11 +37,17 @@
 }
 
 .logoIcon {
+  display: inline-flex;
   width: 36px;
   height: 36px;
   color: var(--accent-coral, #e07256);
 }
 
+.logoIcon svg {
+  width: 100%;
+  height: 100%;
+}
+
 .logoText {
   font-family: var(--font-playfair), 'Playfair Display', serif;
   font-weight: 700;
@@ -126,21 +136,102 @@
   }
 }
 
+/* ─── Bottom tab bar (mobile only) ──────────────────────────────── */
+
+.bottomBar {
+  display: none;
+}
+
+.tab {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  gap: 0.2rem;
+  flex: 1;
+  min-height: 56px;
+  padding: 0.375rem 0.25rem;
+  color: var(--text-secondary, #5c564d);
+  text-decoration: none;
+  font-size: 0.6875rem;
+  font-weight: 500;
+  letter-spacing: 0.01em;
+  transition: color 0.15s ease, background-color 0.15s ease;
+  -webkit-tap-highlight-color: transparent;
+}
+
+.tab:active {
+  background: var(--bg-secondary, #f3ede4);
+}
+
+.tabActive {
+  color: var(--accent-coral, #e07256);
+}
+
+.tabIconWrap {
+  position: relative;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  width: 24px;
+  height: 24px;
+}
+
+.tabIcon {
+  width: 22px;
+  height: 22px;
+}
+
+.tabLabel {
+  line-height: 1;
+}
+
+.tabBadge {
+  position: absolute;
+  top: -6px;
+  right: -10px;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  min-width: 18px;
+  height: 18px;
+  padding: 0 5px;
+  font-size: 0.6875rem;
+  font-weight: 700;
+  color: white;
+  background: var(--accent-coral, #e07256);
+  border: 2px solid var(--bg-card, white);
+  border-radius: 9999px;
+  animation: badgePop 0.3s ease-out;
+}
+
 @media (max-width: 640px) {
   .container {
     padding: 0 1rem;
+    height: 56px;
   }
 
-  .logoText {
+  /* Hide the top text nav; the bottom bar takes over */
+  .nav {
     display: none;
   }
 
-  .nav {
-    gap: 0.25rem;
+  .logoIcon {
+    width: 32px;
+    height: 32px;
   }
 
-  .navLink {
-    padding: 0.5rem 0.75rem;
-    font-size: 0.875rem;
+  .bottomBar {
+    display: flex;
+    position: fixed;
+    bottom: 0;
+    left: 0;
+    right: 0;
+    z-index: 1000;
+    background: var(--bg-card, white);
+    border-top: 1px solid var(--border-color, #e5dfd5);
+    box-shadow: 0 -2px 12px rgba(26, 22, 18, 0.06);
+    /* Respect iPhone home-indicator inset */
+    padding-bottom: env(safe-area-inset-bottom, 0);
   }
 }

nextjs-app/components/Navigation.tsx

@@ -1,6 +1,6 @@
 /**
  * Navigation Component
- * Main navigation header with active link highlighting
+ * Top header nav for desktop; bottom tab bar for mobile (≤640px).
  */
 
 'use client';
@@ -10,63 +10,116 @@ import { usePathname } from 'next/navigation';
 import { useComparison } from '@/hooks/useComparison';
 import styles from './Navigation.module.css';
 
+type IconProps = { className?: string };
+
+const SearchIcon = ({ className }: IconProps) => (
+  <svg className={className} viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
+    <circle cx="11" cy="11" r="7" />
+    <path d="m20 20-3.5-3.5" />
+  </svg>
+);
+
+const CompareIcon = ({ className }: IconProps) => (
+  <svg className={className} viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
+    <path d="M4 7h13l-3-3" />
+    <path d="M20 17H7l3 3" />
+  </svg>
+);
+
+const RankingsIcon = ({ className }: IconProps) => (
+  <svg className={className} viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
+    <path d="M7 21V11" />
+    <path d="M12 21V4" />
+    <path d="M17 21v-7" />
+  </svg>
+);
+
+const AdmissionsIcon = ({ className }: IconProps) => (
+  <svg className={className} viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
+    <rect x="3" y="5" width="18" height="16" rx="2" />
+    <path d="M3 10h18M8 3v4M16 3v4" />
+  </svg>
+);
+
 export function Navigation() {
   const pathname = usePathname();
   const { selectedSchools } = useComparison();
 
   const isActive = (path: string) => {
-    if (path === '/') {
-      return pathname === '/';
-    }
+    if (path === '/') return pathname === '/';
     return pathname.startsWith(path);
   };
 
-  return (
-    <header className={styles.header}>
-      <div className={styles.container}>
-        <Link href="/" className={styles.logo}>
-          <div className={styles.logoIcon}>
-            <svg viewBox="0 0 40 40" fill="none" xmlns="http://www.w3.org/2000/svg">
-              <circle cx="20" cy="20" r="18" stroke="currentColor" strokeWidth="2"/>
-              <path d="M20 6L20 34M8 14L32 14M6 20L34 20M8 26L32 26" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round"/>
-              <circle cx="20" cy="20" r="3" fill="currentColor"/>
-            </svg>
-          </div>
-          <span className={styles.logoText}>SchoolCompare</span>
-        </Link>
+  const items = [
+    { href: '/', label: 'Search', Icon: SearchIcon },
+    { href: '/compare', label: 'Compare', Icon: CompareIcon },
+    { href: '/rankings', label: 'Rankings', Icon: RankingsIcon },
+    { href: '/admissions', label: 'Admissions', Icon: AdmissionsIcon },
+  ] as const;
 
-        <nav className={styles.nav} aria-label="Main navigation">
-          <Link
-            href="/"
-            className={isActive('/') ? `${styles.navLink} ${styles.active}` : styles.navLink}
-          >
-            Search
+  return (
+    <>
+      <header className={styles.header}>
+        <div className={styles.container}>
+          <Link href="/" className={styles.logo} aria-label="SchoolCompare home">
+            <span className={styles.logoIcon}>
+              <svg viewBox="0 0 40 40" fill="none" xmlns="http://www.w3.org/2000/svg" aria-hidden="true">
+                <circle cx="20" cy="20" r="18" stroke="currentColor" strokeWidth="2" />
+                <path d="M20 6L20 34M8 14L32 14M6 20L34 20M8 26L32 26" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" />
+                <circle cx="20" cy="20" r="3" fill="currentColor" />
+              </svg>
+            </span>
+            <span className={styles.logoText}>SchoolCompare</span>
           </Link>
-          <Link
-            href="/compare"
-            className={isActive('/compare') ? `${styles.navLink} ${styles.active}` : styles.navLink}
-          >
-            Compare
-            {selectedSchools.length > 0 && (
-              <span key={selectedSchools.length} className={styles.badge}>
-                {selectedSchools.length}
+
+          <nav className={styles.nav} aria-label="Main navigation">
+            {items.map(({ href, label }) => {
+              const active = isActive(href);
+              const showBadge = href === '/compare' && selectedSchools.length > 0;
+              return (
+                <Link
+                  key={href}
+                  href={href}
+                  className={active ? `${styles.navLink} ${styles.active}` : styles.navLink}
+                  aria-current={active ? 'page' : undefined}
+                >
+                  {label}
+                  {showBadge && (
+                    <span key={selectedSchools.length} className={styles.badge}>
+                      {selectedSchools.length}
+                    </span>
+                  )}
+                </Link>
+              );
+            })}
+          </nav>
+        </div>
+      </header>
+
+      <nav className={styles.bottomBar} aria-label="Main navigation">
+        {items.map(({ href, label, Icon }) => {
+          const active = isActive(href);
+          const showBadge = href === '/compare' && selectedSchools.length > 0;
+          return (
+            <Link
+              key={href}
+              href={href}
+              className={active ? `${styles.tab} ${styles.tabActive}` : styles.tab}
+              aria-current={active ? 'page' : undefined}
+            >
+              <span className={styles.tabIconWrap}>
+                <Icon className={styles.tabIcon} />
+                {showBadge && (
+                  <span key={selectedSchools.length} className={styles.tabBadge} aria-label={`${selectedSchools.length} selected`}>
+                    {selectedSchools.length}
+                  </span>
+                )}
               </span>
-            )}
-          </Link>
-          <Link
-            href="/rankings"
-            className={isActive('/rankings') ? `${styles.navLink} ${styles.active}` : styles.navLink}
-          >
-            Rankings
-          </Link>
-          <Link
-            href="/admissions"
-            className={isActive('/admissions') ? `${styles.navLink} ${styles.active}` : styles.navLink}
-          >
-            Admissions
-          </Link>
-        </nav>
-      </div>
-    </header>
+              <span className={styles.tabLabel}>{label}</span>
+            </Link>
+          );
+        })}
+      </nav>
+    </>
   );
 }