diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6fefab3c..9099f793 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -50,6 +50,13 @@ jobs:
       - name: Type check
         run: pnpm type-check
 
+      # The script existed and already failed — CSS said `sm` was 430px while
+      # src/config/breakpoints.ts said 428px — and it was wired into no workflow
+      # and no hook (#373 B2). Landing it green here is what keeps the two in
+      # step; without this step the mirror silently drifts again.
+      - name: Validate breakpoint configuration
+        run: pnpm validate:breakpoints
+
       - name: Run tests
         run: pnpm test --run
 
diff --git a/scripts/validate-ci.sh b/scripts/validate-ci.sh
index ef4ac064..626e311e 100755
--- a/scripts/validate-ci.sh
+++ b/scripts/validate-ci.sh
@@ -83,6 +83,11 @@ run_check "ESLint" "pnpm lint"
 # 2. Type check
 run_check "TypeScript type check" "pnpm type-check"
 
+# 2b. Breakpoint drift. The script existed and already failed — CSS said the `sm`
+# breakpoint was 430px while src/config/breakpoints.ts said 428px — and it was
+# wired into no workflow and no hook, so nothing ever ran it (#373 B2).
+run_check "Breakpoint config" "pnpm validate:breakpoints"
+
 # 3. Unit tests
 run_check "Unit tests" "pnpm test --run"
 
diff --git a/src/app/accessibility/page.tsx b/src/app/accessibility/page.tsx
index 697aa1bd..b10c73e2 100644
--- a/src/app/accessibility/page.tsx
+++ b/src/app/accessibility/page.tsx
@@ -9,7 +9,7 @@ export default function AccessibilityPage() {
   const { fontSize, lineHeight, fontFamily } = settings;
 
   return (
-    <main className="bg-base-100 min-h-screen">
+    <main className="bg-base-100 min-h-full">
       <div className="mx-auto w-full px-4 py-6 sm:py-8 md:py-12">
         <div className="mx-auto max-w-4xl">
           <h1 className="mb-6 !text-2xl font-bold sm:mb-8 sm:!text-4xl md:!text-5xl">
diff --git a/src/app/contact/page.tsx b/src/app/contact/page.tsx
index db3eb5e5..cd4250d6 100644
--- a/src/app/contact/page.tsx
+++ b/src/app/contact/page.tsx
@@ -15,7 +15,7 @@ export const metadata: Metadata = {
 
 export default function ContactPage() {
   return (
-    <main className="mx-auto min-h-screen w-full px-4 py-6 sm:py-8 md:py-12">
+    <main className="mx-auto min-h-full w-full px-4 py-6 sm:py-8 md:py-12">
       <div className="mx-auto max-w-4xl">
         <div className="mb-8 text-center">
           <h1 className="mb-4 !text-2xl font-bold sm:!text-4xl md:!text-5xl">
diff --git a/src/app/globals.css b/src/app/globals.css
index f42b2a12..80b7d029 100644
--- a/src/app/globals.css
+++ b/src/app/globals.css
@@ -1190,7 +1190,7 @@ p:not([class*='text-']) {
   line-height: 1 !important;
 }
 
-@media (min-width: 26.75rem) {
+@media (width >= theme(--breakpoint-sm)) {
   .btn-mobile-compact {
     height: 2rem !important;
     min-height: 2rem !important;
@@ -1211,7 +1211,7 @@ p:not([class*='text-']) {
   margin-bottom: 0.25rem !important;
 }
 
-@media (min-width: 26.75rem) {
+@media (width >= theme(--breakpoint-sm)) {
   /* sm breakpoint */
   .page-title {
     font-size: var(--text-2xl) !important;
@@ -1252,7 +1252,7 @@ p:not([class*='text-']) {
   font-weight: 600 !important;
 }
 
-@media (min-width: 26.75rem) {
+@media (width >= theme(--breakpoint-sm)) {
   .section-title {
     font-size: var(--text-xl) !important;
     margin-top: 1rem !important;
@@ -1292,7 +1292,7 @@ p:not([class*='text-']) {
   margin-bottom: 0.25rem !important;
 }
 
-@media (min-width: 26.75rem) {
+@media (width >= theme(--breakpoint-sm)) {
   .subsection-title {
     font-size: var(--text-lg) !important;
     margin-top: 0.75rem !important;
@@ -1324,7 +1324,7 @@ p:not([class*='text-']) {
   margin-bottom: 0.125rem !important;
 }
 
-@media (min-width: 26.75rem) {
+@media (width >= theme(--breakpoint-sm)) {
   .minor-heading {
     font-size: var(--text-base) !important;
     margin-top: 0.5rem !important;
diff --git a/src/app/layout.tsx b/src/app/layout.tsx
index 562c252f..c1051d14 100644
--- a/src/app/layout.tsx
+++ b/src/app/layout.tsx
@@ -186,7 +186,7 @@ export default function RootLayout({
               <CountdownBanner />
               <SetupBanner />
               <ErrorBoundary level="page">
-                <div className="bg-base-200 min-h-0 flex-1 overflow-hidden pb-14">
+                <div className="bg-base-200 min-h-0 flex-1 overflow-x-clip">
                   {children}
                 </div>
               </ErrorBoundary>
diff --git a/src/app/messages/setup/page.tsx b/src/app/messages/setup/page.tsx
index e8edf990..c52e0ffb 100644
--- a/src/app/messages/setup/page.tsx
+++ b/src/app/messages/setup/page.tsx
@@ -156,7 +156,7 @@ export default function MessagingSetupPage() {
   // Loading states
   if (authLoading || checkingKeys) {
     return (
-      <div className="flex min-h-screen items-center justify-center">
+      <div className="flex min-h-full items-center justify-center">
         <span className="loading loading-spinner loading-lg"></span>
       </div>
     );
@@ -165,7 +165,7 @@ export default function MessagingSetupPage() {
   // Redirect if already set up
   if (hasExistingKeys) {
     return (
-      <div className="flex min-h-screen items-center justify-center">
+      <div className="flex min-h-full items-center justify-center">
         <span className="loading loading-spinner loading-lg"></span>
         <span className="ml-2">Redirecting to messages...</span>
       </div>
@@ -173,7 +173,7 @@ export default function MessagingSetupPage() {
   }
 
   return (
-    <div className="flex min-h-screen items-center justify-center p-4">
+    <div className="flex min-h-full items-center justify-center p-4">
       <div className="card bg-base-100 rounded-box w-full max-w-md">
         <div className="card-body">
           <h1 className="card-title text-2xl">Set Up Encrypted Messaging</h1>
diff --git a/src/app/not-found.tsx b/src/app/not-found.tsx
index 8040884c..6d032c40 100644
--- a/src/app/not-found.tsx
+++ b/src/app/not-found.tsx
@@ -2,7 +2,7 @@ import Link from 'next/link';
 
 export default function NotFound() {
   return (
-    <div className="flex min-h-screen flex-col items-center justify-center">
+    <div className="flex min-h-full flex-col items-center justify-center">
       <div className="text-center">
         <h1 className="mb-4 text-6xl font-bold">404</h1>
         <h2 className="mb-4 text-2xl">Page Not Found</h2>
diff --git a/src/app/themes/page.tsx b/src/app/themes/page.tsx
index 8eb58eb1..757e0ad2 100644
--- a/src/app/themes/page.tsx
+++ b/src/app/themes/page.tsx
@@ -80,7 +80,7 @@ export default function ThemesPage() {
   };
 
   return (
-    <main className="bg-base-100 min-h-screen">
+    <main className="bg-base-100 min-h-full">
       <div className="container mx-auto px-4 py-6 sm:py-8 md:py-12">
         <header className="mb-8">
           <p className="text-base-content mb-2 font-mono text-xs tracking-wider uppercase">
diff --git a/src/components/GlobalNav.tsx b/src/components/GlobalNav.tsx
index cc129054..2294ccb5 100644
--- a/src/components/GlobalNav.tsx
+++ b/src/components/GlobalNav.tsx
@@ -182,6 +182,14 @@ function NavGroupMenu({
   );
 }
 
+/**
+ * Every item in a DaisyUI `menu` needs an explicit height floor: `li > a`
+ * renders at 26px, and the 44px gate cannot see items inside a closed
+ * dropdown, so they stay under it indefinitely (#378). Named rather than
+ * repeated so a new entry cannot arrive without one.
+ */
+const MENU_ITEM = 'min-h-11 flex items-center';
+
 /** A single nav destination. */
 type NavLeaf = { href: string; label: string; reload?: boolean };
 /** A labelled group of destinations, rendered as a dropdown. */
@@ -519,10 +527,14 @@ export function GlobalNav() {
                     <span>{user.email}</span>
                   </li>
                   <li>
-                    <Link href="/profile">Profile</Link>
+                    <Link href="/profile" className={MENU_ITEM}>
+                      Profile
+                    </Link>
                   </li>
                   <li>
-                    <Link href="/account">Account Settings</Link>
+                    <Link href="/account" className={MENU_ITEM}>
+                      Account Settings
+                    </Link>
                   </li>
                   <li>
                     <Link
@@ -538,11 +550,18 @@ export function GlobalNav() {
                     </Link>
                   </li>
                   <li>
-                    <Link href="/messages?tab=connections">Connections</Link>
+                    <Link
+                      href="/messages?tab=connections"
+                      className={MENU_ITEM}
+                    >
+                      Connections
+                    </Link>
                   </li>
                   {isAdmin && (
                     <li>
-                      <Link href="/admin">Admin Dashboard</Link>
+                      <Link href="/admin" className={MENU_ITEM}>
+                        Admin Dashboard
+                      </Link>
                     </li>
                   )}
                   <li>
@@ -624,14 +643,14 @@ export function GlobalNav() {
                     {item.reload ? (
                       <a
                         href={getInternalUrl(item.href)}
-                        className={isActive(item) ? 'active' : ''}
+                        className={`${MENU_ITEM} ${isActive(item) ? 'active' : ''}`}
                       >
                         {item.label}
                       </a>
                     ) : (
                       <Link
                         href={item.href}
-                        className={isActive(item) ? 'active' : ''}
+                        className={`${MENU_ITEM} ${isActive(item) ? 'active' : ''}`}
                       >
                         {item.label}
                       </Link>
@@ -644,15 +663,19 @@ export function GlobalNav() {
                       <span>Account</span>
                     </li>
                     <li>
-                      <Link href="/profile">Profile</Link>
+                      <Link href="/profile" className={MENU_ITEM}>
+                        Profile
+                      </Link>
                     </li>
                     <li>
-                      <Link href="/account">Settings</Link>
+                      <Link href="/account" className={MENU_ITEM}>
+                        Settings
+                      </Link>
                     </li>
                     <li>
                       <Link
                         href="/messages"
-                        className="flex items-center justify-between"
+                        className={`${MENU_ITEM} justify-between`}
                       >
                         <span>Messages</span>
                         {unreadCount > 0 && (
@@ -663,11 +686,18 @@ export function GlobalNav() {
                       </Link>
                     </li>
                     <li>
-                      <Link href="/messages?tab=connections">Connections</Link>
+                      <Link
+                        href="/messages?tab=connections"
+                        className={MENU_ITEM}
+                      >
+                        Connections
+                      </Link>
                     </li>
                     {isAdmin && (
                       <li>
-                        <Link href="/admin">Admin Dashboard</Link>
+                        <Link href="/admin" className={MENU_ITEM}>
+                          Admin Dashboard
+                        </Link>
                       </li>
                     )}
                     <li>
@@ -695,10 +725,14 @@ export function GlobalNav() {
                       <span>Account</span>
                     </li>
                     <li>
-                      <Link href="/sign-in">Sign In</Link>
+                      <Link href="/sign-in" className={MENU_ITEM}>
+                        Sign In
+                      </Link>
                     </li>
                     <li>
-                      <Link href="/sign-up">Sign Up</Link>
+                      <Link href="/sign-up" className={MENU_ITEM}>
+                        Sign Up
+                      </Link>
                     </li>
                   </>
                 )}
@@ -774,7 +808,7 @@ export function GlobalNav() {
                 <h3 className="mb-2 text-sm font-semibold tracking-wide uppercase">
                   Theme
                 </h3>
-                <ul className="max-h-64 overflow-y-auto">
+                <ul>
                   {THEMES.map((t) => (
                     <li key={t}>
                       <button
diff --git a/src/components/auth/AuthGuard/AuthGuard.tsx b/src/components/auth/AuthGuard/AuthGuard.tsx
index fee302b3..8891b72e 100644
--- a/src/components/auth/AuthGuard/AuthGuard.tsx
+++ b/src/components/auth/AuthGuard/AuthGuard.tsx
@@ -36,7 +36,7 @@ export default function AuthGuard({
 
   if (isLoading) {
     return (
-      <div className="flex min-h-screen items-center justify-center">
+      <div className="flex min-h-full items-center justify-center">
         <span className="loading loading-spinner loading-lg"></span>
       </div>
     );
diff --git a/src/components/auth/ProtectedRoute/ProtectedRoute.tsx b/src/components/auth/ProtectedRoute/ProtectedRoute.tsx
index a57631dc..67cbc5f7 100644
--- a/src/components/auth/ProtectedRoute/ProtectedRoute.tsx
+++ b/src/components/auth/ProtectedRoute/ProtectedRoute.tsx
@@ -64,7 +64,7 @@ export default function ProtectedRoute({
 
   if (isLoading) {
     return (
-      <div className="flex min-h-screen items-center justify-center">
+      <div className="flex min-h-full items-center justify-center">
         <span className="loading loading-spinner loading-lg"></span>
       </div>
     );
@@ -76,7 +76,7 @@ export default function ProtectedRoute({
   // sign-out the component unmounts via window.location.href anyway.
   if (!isAuthenticated && !wasAuthenticated.current) {
     return (
-      <div className="flex min-h-screen items-center justify-center px-4">
+      <div className="flex min-h-full items-center justify-center px-4">
         <div className="card bg-base-100 w-full max-w-md shadow-xl">
           <div className="card-body items-center text-center">
             <svg
diff --git a/src/components/molecular/ColorblindToggle/ColorblindToggle.tsx b/src/components/molecular/ColorblindToggle/ColorblindToggle.tsx
index 126bc5ef..ddcfcb32 100644
--- a/src/components/molecular/ColorblindToggle/ColorblindToggle.tsx
+++ b/src/components/molecular/ColorblindToggle/ColorblindToggle.tsx
@@ -66,7 +66,14 @@ export const ColorVisionPanel: React.FC = () => {
 
   return (
     <div>
-      <h3 className="text-lg font-bold">Color Vision Assistance</h3>
+      {/* A SECTION LABEL, not a page heading (#469). As a standalone popover
+          this was `text-lg font-bold`; inside `Display ▾` that put it a whole
+          tier above the "TEXT SETTINGS" and "THEME" labels beside it, and it
+          wrapped to two lines at 390px — measured 25.7px/80px against their
+          18.5px/26px. */}
+      <h3 className="mb-2 text-sm font-semibold tracking-wide uppercase">
+        Color Vision Assistance
+      </h3>
 
       <div>
         <label className="label" htmlFor={selectId}>
@@ -105,8 +112,15 @@ export const ColorVisionPanel: React.FC = () => {
         </div>
       )}
 
-      <div className="alert alert-info mt-4" role="status" aria-live="polite">
-        <span className="text-sm">
+      {/* A hint line, not an `alert` (#469): the tinted block measured 105px
+          for one sentence inside a menu. `role="status"` and `aria-live` stay —
+          the announcement when the mode changes is the point of this text. */}
+      <div
+        className="text-base-content mt-3 text-sm"
+        role="status"
+        aria-live="polite"
+      >
+        <span>
           {mode === ColorblindType.NONE
             ? 'Select your color vision type for visual assistance'
             : `Correcting for ${COLORBLIND_LABELS[mode]}`}
diff --git a/src/config/breakpoints.ts b/src/config/breakpoints.ts
index 3aff69a8..1abaaedb 100644
--- a/src/config/breakpoints.ts
+++ b/src/config/breakpoints.ts
@@ -13,27 +13,35 @@ import type { BreakpointConfig } from '@/types/mobile-first';
  *
  * Strategy: Mobile-first with progressive enhancement
  * - xs (320px): Minimum supported mobile width
- * - sm (428px): Standard mobile devices
+ * - sm (430px): Standard mobile devices
  * - md (768px): Tablet portrait
  * - lg (1024px): Desktop and tablet landscape
  * - xl (1280px): Large desktop
  *
- * Note: Tailwind CSS 4 uses `@theme` in globals.css for configuration
+ * Note: Tailwind CSS 4 uses `@theme` in globals.css for configuration, which is
+ * the SOURCE OF TRUTH — this file mirrors it, and `pnpm validate:breakpoints`
+ * fails when the two disagree.
+ *
+ * `sm` is 430px, not 428px, deliberately: the iPhone 14 Pro Max is exactly 428
+ * CSS px, and it is a phone, so `sm:` utilities must NOT apply there. That is
+ * also why `xs` ends at 429 rather than 427 — 428 and 429 belong to the phone
+ * bucket. This file said 428 while globals.css said 430, so at 428-429px the
+ * hand-written media queries fired and no Tailwind `sm:` utility did (#373 B2).
  */
 export const BREAKPOINTS: BreakpointConfig[] = [
   {
     name: 'xs',
     minWidth: 320,
-    maxWidth: 427,
+    maxWidth: 429,
     category: 'mobile',
-    mediaQuery: '(min-width: 320px) and (max-width: 427px)',
+    mediaQuery: '(min-width: 320px) and (max-width: 429px)',
   },
   {
     name: 'sm',
-    minWidth: 428,
+    minWidth: 430,
     maxWidth: 767,
     category: 'mobile',
-    mediaQuery: '(min-width: 428px) and (max-width: 767px)',
+    mediaQuery: '(min-width: 430px) and (max-width: 767px)',
   },
   {
     name: 'md',
@@ -105,8 +113,8 @@ export function getDeviceCategory(width: number): string {
 export const mediaQueries = {
   /** Mobile and up (>= 320px) */
   mobile: '(min-width: 320px)',
-  /** Standard mobile and up (>= 428px) */
-  sm: '(min-width: 428px)',
+  /** Standard mobile and up (>= 430px) */
+  sm: '(min-width: 430px)',
   /** Tablet and up (>= 768px) */
   md: '(min-width: 768px)',
   /** Desktop and up (>= 1024px) */
diff --git a/tests/e2e/tests/mobile-touch-targets.spec.ts b/tests/e2e/tests/mobile-touch-targets.spec.ts
index 8cc1cafa..5aea7f26 100644
--- a/tests/e2e/tests/mobile-touch-targets.spec.ts
+++ b/tests/e2e/tests/mobile-touch-targets.spec.ts
@@ -198,6 +198,71 @@ test.describe('Touch Target Standards', () => {
     ).toBeGreaterThanOrEqual(7);
   });
 
+  test("the mobile menu's own items meet 44px (#378)", async ({ page }) => {
+    test.setTimeout(90000);
+
+    // THE EXEMPTION THIS CLOSES.
+    //
+    // The primary-button selector above is
+    // `nav button, nav label, a.btn, a.sh-btn, button.sh-btn`, and its coverage
+    // note says bare `<a>` items are exempt as "inline text links". That is true
+    // of a link in a paragraph. It is not true of these: below lg they are the
+    // ENTIRE navigation. Measured before the fix, at 390px with the menu open,
+    // all 13 destinations were 26x144 against a 44px floor — DaisyUI renders
+    // `menu li > a` at 26px, and nothing here could see them because they sit
+    // inside a closed dropdown.
+    for (const width of [320, 390, 428, 768]) {
+      await page.setViewportSize({ width, height: 900 });
+      await page.goto('/', { waitUntil: 'domcontentloaded' });
+      await dismissCookieBanner(page);
+      await waitForLayoutStability(page);
+
+      const trigger = page.locator('[aria-label="Navigation menu"]');
+      await expect(trigger).toBeVisible();
+      await trigger.click();
+
+      const items = page.locator(
+        '.dropdown-content a, .dropdown-content button'
+      );
+      const count = await items.count();
+
+      // COVERAGE FLOOR. Everything below is conditional on finding items, so a
+      // menu that failed to open would pass silently — the #411/#454 shape. 13
+      // is MEASURED signed-out at each of these widths.
+      expect(
+        count,
+        `only ${count} items measured in the mobile menu at ${width}px — it ` +
+          `probably did not open`
+      ).toBeGreaterThanOrEqual(13);
+
+      const failures: string[] = [];
+      for (let i = 0; i < count; i++) {
+        const el = items.nth(i);
+        if (!(await el.isVisible())) continue;
+        const box = await el.boundingBox();
+        if (!box) continue;
+        if (
+          box.height < MINIMUM - TOLERANCE ||
+          box.width < MINIMUM - TOLERANCE
+        ) {
+          const name =
+            (await el.textContent())?.trim().slice(0, 24) || '(unnamed)';
+          failures.push(
+            `${name}: ${box.width.toFixed(0)}x${box.height.toFixed(0)}px at ${width}px`
+          );
+        }
+      }
+
+      expect(
+        failures,
+        `${failures.length} mobile menu items under ${MINIMUM}px at ${width}px. ` +
+          `These are the whole navigation below lg:\n${failures.join('\n')}`
+      ).toEqual([]);
+
+      await page.keyboard.press('Escape');
+    }
+  });
+
   test('the Demos menu is keyboard operable and Escape restores focus (#378)', async ({
     page,
   }) => {