diff --git a/web/src/app/globals.css b/web/src/app/globals.css
index b917486..51be4a2 100644
--- a/web/src/app/globals.css
+++ b/web/src/app/globals.css
@@ -239,22 +239,31 @@ button:active:not(:disabled), [role="button"]:active:not(:disabled) {
 /* Responsive sidebar */
 @media (max-width: 768px) {
   .app-sidebar {
-    position: fixed;
-    left: -260px;
-    top: 0;
+    position: fixed !important;
+    left: -280px !important;
+    top: 0 !important;
     z-index: 40;
-    width: 240px;
-    height: 100vh;
+    width: 260px !important;
+    height: 100vh !important;
     transition: left 0.2s ease;
+    overflow-y: auto;
   }
-  .app-sidebar.open { left: 0; }
+  .app-sidebar.open { left: 0 !important; }
   .sidebar-overlay { display: none; position: fixed; inset: 0; z-index: 39; background: rgba(0,0,0,0.5); }
   .sidebar-overlay.open { display: block; }
-  .sidebar-toggle { display: flex; }
+  .sidebar-toggle {
+    display: flex; align-items: center; justify-content: center;
+    position: fixed; top: 12px; left: 12px; z-index: 38;
+    width: 40px; height: 40px; border-radius: 8px;
+    border: 1px solid var(--nl-border-default, #2a2a4a);
+    background: var(--nl-bg-elevated, #12151c);
+    color: var(--nl-text-primary, #fff);
+    cursor: pointer; font-size: 20px; line-height: 1;
+  }
 }
 @media (min-width: 769px) {
-  .sidebar-toggle { display: none; }
-  .sidebar-overlay { display: none; }
+  .sidebar-toggle { display: none !important; }
+  .sidebar-overlay { display: none !important; }
 }
 
 /* Respect user motion preference */
diff --git a/web/src/components/AppShell.tsx b/web/src/components/AppShell.tsx
index 5754cb6..0e25652 100644
--- a/web/src/components/AppShell.tsx
+++ b/web/src/components/AppShell.tsx
@@ -1,4 +1,7 @@
-import type { ReactNode } from "react";
+"use client";
+
+import { type ReactNode, useState, useCallback, useEffect } from "react";
+import { usePathname } from "next/navigation";
 import { Sidebar } from "@/components/Sidebar";
 
 export function AppShell({
@@ -12,12 +15,35 @@ export function AppShell({
   actions?: ReactNode;
   children: ReactNode;
 }) {
+  const [sidebarOpen, setSidebarOpen] = useState(false);
+  const pathname = usePathname();
+
+  useEffect(() => {
+    setSidebarOpen(false);
+  }, [pathname]);
+
+  const toggle = useCallback(() => setSidebarOpen((o) => !o), []);
+  const close = useCallback(() => setSidebarOpen(false), []);
+
   return (
     <div className="app-shell">
       <a href="#main-content" className="skip-link">
         Skip to main content
       </a>
-      <Sidebar />
+      <button
+        className="sidebar-toggle"
+        onClick={toggle}
+        aria-label={sidebarOpen ? "Close menu" : "Open menu"}
+        type="button"
+      >
+        {sidebarOpen ? "\u2715" : "\u2630"}
+      </button>
+      <div
+        className={`sidebar-overlay${sidebarOpen ? " open" : ""}`}
+        onClick={close}
+        aria-hidden="true"
+      />
+      <Sidebar open={sidebarOpen} />
       <main id="main-content" className="main-panel" tabIndex={-1} aria-labelledby="page-title">
         <div className="page-grid">
           <header
diff --git a/web/src/components/Sidebar.tsx b/web/src/components/Sidebar.tsx
index 472e87f..2641535 100644
--- a/web/src/components/Sidebar.tsx
+++ b/web/src/components/Sidebar.tsx
@@ -14,11 +14,11 @@ const navItems: { href: string; label: string; icon: typeof House; flag?: string
   { href: "/settings", label: "Settings", icon: Settings },
 ];
 
-export function Sidebar() {
+export function Sidebar({ open }: { open?: boolean }) {
   const pathname = usePathname() ?? "";
 
   return (
-    <aside className="sidebar" style={{ padding: "var(--nl-space-6)" }} aria-label="Primary">
+    <aside className={`sidebar app-sidebar${open ? ' open' : ''}`} style={{ padding: "var(--nl-space-6)" }} aria-label="Primary">
       <div style={{ display: "grid", gap: "var(--nl-space-6)" }}>
         <div className="surface-card" style={{ padding: "var(--nl-space-5)", display: "grid", gap: "var(--nl-space-3)" }}>
           <div className="badge" style={{ width: "fit-content" }}>