diff --git a/components/Layout.js b/components/Layout.js
index 47df0e8..d07f8e9 100644
--- a/components/Layout.js
+++ b/components/Layout.js
@@ -87,12 +87,10 @@ function UserProfileDropdown({ user, onMobileMenuClose }) {
           
           {/* Menu — Liquid Glass popover, high-tint w/ ember-subtle rim. */}
           <div
-            className="absolute bottom-full left-0 right-0 mb-2 rounded-xl z-20"
+            className="glass-panel-strong absolute bottom-full left-0 right-0 mb-2 rounded-xl z-20"
             style={{
-              background: 'var(--glass-surface-high)',
-              backdropFilter: 'blur(var(--glass-blur-mid)) saturate(var(--glass-saturate))',
-              WebkitBackdropFilter: 'blur(var(--glass-blur-mid)) saturate(var(--glass-saturate))',
-              boxShadow: 'var(--rim-light-inner), var(--ember-rim-subtle), var(--elevation-ambient)',
+              boxShadow:
+                'var(--rim-light-inner), var(--ember-rim-subtle), var(--elevation-ambient)',
             }}
           >
             <div className="py-2">
@@ -693,14 +691,12 @@ export default function Layout({ children, user = null, showSearch = false }) {
       {/* Mobile Menu Drawer - Slides in from left when "More" is tapped */}
       <div
         className={`
-          md:hidden fixed inset-y-0 left-0 z-50 w-64 transform transition-transform duration-300 ease-in-out
+          glass-panel-strong md:hidden fixed inset-y-0 left-0 z-50 w-64 transform transition-transform duration-300 ease-in-out
           ${isMobileMenuOpen ? 'translate-x-0' : '-translate-x-full'}
         `}
         style={{
-          background: 'var(--glass-surface-mid)',
-          backdropFilter: 'blur(var(--glass-blur-mid)) saturate(var(--glass-saturate))',
-          WebkitBackdropFilter: 'blur(var(--glass-blur-mid)) saturate(var(--glass-saturate))',
-          boxShadow: 'var(--rim-light-inner), var(--rim-light-outer), var(--elevation-pronounced)',
+          boxShadow:
+            'var(--rim-light-inner), var(--rim-light-outer), var(--elevation-pronounced)',
         }}
       >
         <div className="p-4 h-full flex flex-col">
diff --git a/components/ui/TopSearchBar.js b/components/ui/TopSearchBar.js
index ce2ca06..1e3b409 100644
--- a/components/ui/TopSearchBar.js
+++ b/components/ui/TopSearchBar.js
@@ -211,11 +211,8 @@ function UserMenu({ user }) {
           <div
             role="menu"
             aria-label="Account menu"
-            className="absolute right-0 top-full mt-2 w-56 rounded-xl z-30 overflow-hidden"
+            className="glass-panel-strong absolute right-0 top-full mt-2 w-56 rounded-xl z-30 overflow-hidden"
             style={{
-              background: 'var(--glass-surface-high)',
-              backdropFilter: 'blur(var(--glass-blur-mid)) saturate(var(--glass-saturate))',
-              WebkitBackdropFilter: 'blur(var(--glass-blur-mid)) saturate(var(--glass-saturate))',
               boxShadow:
                 'var(--rim-light-inner), var(--ember-rim-subtle), var(--elevation-pronounced)',
             }}
diff --git a/test/components/Layout.test.js b/test/components/Layout.test.js
index 2bdd866..49d9373 100644
--- a/test/components/Layout.test.js
+++ b/test/components/Layout.test.js
@@ -88,3 +88,49 @@ describe('Layout — logged-out rendering (regression: P0 #7)', () => {
     expect(container.textContent).not.toContain('Guest');
   });
 });
+
+describe('Layout — floating popovers use .glass-panel-strong (regression: Brief 3 of unify-glass-panel-surfaces)', () => {
+  afterEach(() => cleanup());
+
+  // The sidebar UserProfileDropdown and the mobile drawer are floating
+  // glass surfaces. Brief 3 migrated them from inline
+  // `background: var(--glass-surface-*)` + `backdropFilter` to the
+  // canonical `.glass-panel-strong` className. If a future PR reverts
+  // either to the inline pattern, the bespoke-glass-surface CI gate
+  // (Brief 7) will catch the regression — these unit tests catch the
+  // SAME regression at the component-render level, before the gate
+  // would fire.
+
+  it('mobile drawer panel carries .glass-panel-strong when isMobileMenuOpen', () => {
+    const { container } = render(
+      <Layout user={{ email: 'foo@bar.com', role: 'user' }}>page body</Layout>
+    );
+    // The drawer is rendered (translated off-screen via `-translate-x-full`)
+    // even when closed, so we can assert on it from a default mount.
+    const drawer = container.querySelector(
+      '.glass-panel-strong.md\\:hidden.fixed.inset-y-0.left-0'
+    );
+    expect(drawer).not.toBeNull();
+    expect(drawer.className).toContain('glass-panel-strong');
+    expect(drawer.className).toContain('w-64');
+  });
+
+  it('mobile drawer panel does NOT carry an inline `background: var(--glass-surface-*)` style after Brief 3', () => {
+    // Regression lock against reverting Brief 3 to handrolled inline
+    // glass styles on the mobile drawer specifically. The drawer is
+    // always in the DOM (translated off-screen when closed), so we can
+    // query it from a default mount.
+    const { container } = render(
+      <Layout user={{ email: 'foo@bar.com', role: 'user' }}>page body</Layout>
+    );
+    const drawer = container.querySelector(
+      '.glass-panel-strong.md\\:hidden.fixed.inset-y-0.left-0'
+    );
+    expect(drawer).not.toBeNull();
+    const inlineStyle = drawer.getAttribute('style') ?? '';
+    expect(inlineStyle).not.toMatch(/var\(--glass-surface-/);
+    expect(inlineStyle).not.toMatch(/backdrop-filter/i);
+    expect(inlineStyle).toContain('box-shadow');
+    expect(inlineStyle).toContain('--elevation-pronounced');
+  });
+});