diff --git a/apps/web/src/layout/AppLayout.tsx b/apps/web/src/layout/AppLayout.tsx
index cd0ab18..afae63a 100644
--- a/apps/web/src/layout/AppLayout.tsx
+++ b/apps/web/src/layout/AppLayout.tsx
@@ -64,7 +64,10 @@ export function AppLayout(): React.JSX.Element {
             <Sidebar collapsed={collapsed} />
             {!collapsed && <SidebarResizer widthRem={widthRem} onResize={setSidebarWidth} />}
             <div className="main-column">
-              <main className="main">
+              {/* tabIndex: the main area is the app's scroll container; on
+                  pages without focusable content (e.g. legal texts) keyboard
+                  users could otherwise not scroll it (#165, WCAG 2.1.1). */}
+              <main className="main" tabIndex={0}>
                 <Outlet />
               </main>
               {/* Outside the scroll container: always visible at the bottom
diff --git a/apps/web/src/layout/TopBar.tsx b/apps/web/src/layout/TopBar.tsx
index ee9fff5..577d42f 100644
--- a/apps/web/src/layout/TopBar.tsx
+++ b/apps/web/src/layout/TopBar.tsx
@@ -96,7 +96,8 @@ export function TopBar({ sidebarCollapsed, onToggleSidebar }: TopBarProps): Reac
           onClick={() => setSearchOpen(true)}
           aria-label={t('search:open')}
         >
-          <Search aria-hidden /> {t('search:open')}
+          <Search aria-hidden />
+          <span className="topbar__search-text">{t('search:open')}</span>
         </button>
       )}
       {searchOpen && user && <SearchPalette onClose={() => setSearchOpen(false)} />}
diff --git a/apps/web/src/styles/base.css b/apps/web/src/styles/base.css
index 3cedb5a..4dc4299 100644
--- a/apps/web/src/styles/base.css
+++ b/apps/web/src/styles/base.css
@@ -53,7 +53,9 @@ button {
 /* Layout skeleton */
 .app {
   display: grid;
-  grid-template-rows: var(--topbar-height) 1fr;
+  /* minmax: the topbar row may grow when its controls wrap on narrow
+     viewports (issue #165, WCAG 1.4.10). */
+  grid-template-rows: minmax(var(--topbar-height), auto) 1fr;
   height: 100%;
 }
 
@@ -70,6 +72,10 @@ button {
   align-items: center;
   gap: var(--space-4);
   padding: 0 var(--space-4);
+  /* Same #100 pattern as .app-body: without this the topbar's min-content
+     width sizes the shared grid column and forces page-level horizontal
+     scrolling on narrow viewports (issue #165, WCAG 1.4.10). */
+  min-width: 0;
   border-bottom: 1px solid var(--color-border);
   background: var(--color-bg);
   /* Own stacking context above the scrolling `.main` content: the nav comes
@@ -91,6 +97,39 @@ button {
   flex: 1;
 }
 
+/* Narrow viewports (issue #165, WCAG 1.4.10): the topbar wraps onto a
+   second row instead of pushing the page wider than the viewport; every
+   control stays visible and reachable. The search button drops to its
+   icon (the aria-label carries the name). The expanded sidebar becomes
+   an overlay above the content — 256 px beside a 320 px viewport would
+   leave the content a sliver and force page-level horizontal scrolling. */
+@media (max-width: 40rem) {
+  .topbar {
+    flex-wrap: wrap;
+    row-gap: 0;
+    padding: var(--space-1) var(--space-2);
+  }
+
+  .topbar__search-text {
+    display: none;
+  }
+
+  .app-body {
+    position: relative;
+  }
+
+  .sidebar:not(.sidebar--collapsed) {
+    position: absolute;
+    inset: 0 auto 0 0;
+    z-index: 25;
+    box-shadow: 2px 0 8px rgb(0 0 0 / 0.15);
+  }
+
+  .sidebar-resizer {
+    display: none;
+  }
+}
+
 .sidebar {
   width: var(--sidebar-width);
   flex-shrink: 0;
@@ -715,6 +754,9 @@ button {
   align-items: center;
   gap: var(--space-2);
   flex-shrink: 0;
+  /* Wrap instead of widening the page on narrow viewports (#165). */
+  flex-wrap: wrap;
+  min-width: 0;
   padding: var(--space-2) var(--space-8);
   border-top: 1px solid var(--color-border);
   background: var(--color-bg);
@@ -958,6 +1000,9 @@ button {
 
 .editor-page__title {
   flex: 1;
+  /* An input's intrinsic size-attribute width must not set the page's
+     minimum width on narrow viewports (#165). */
+  min-width: 0;
   border: none;
   background: none;
   font-family: var(--font-heading);
@@ -3784,6 +3829,9 @@ ul[data-type='task_list'] li p:last-of-type {
 @media (max-width: 60rem) {
   .settings-layout {
     flex-direction: column;
+    /* Override the row layout's flex-start: stacked, the content column
+       must stretch to the viewport instead of its widest control (#165). */
+    align-items: stretch;
   }
 
   .settings-nav {