diff --git a/src/app/layout/AppShell.tsx b/src/app/layout/AppShell.tsx
index 34a8c2b..7618980 100644
--- a/src/app/layout/AppShell.tsx
+++ b/src/app/layout/AppShell.tsx
@@ -1,4 +1,4 @@
-import type { PropsWithChildren, ReactNode } from 'react';
+import { useState, type PropsWithChildren, type ReactNode } from 'react';
 
 interface AppShellProps extends PropsWithChildren {
   toolbar: ReactNode;
@@ -8,13 +8,50 @@ interface AppShellProps extends PropsWithChildren {
 }
 
 export default function AppShell({ toolbar, sidebar, inspector, statusbar, children }: AppShellProps) {
+  const [mobilePanel, setMobilePanel] = useState<'sidebar' | 'inspector' | null>(null);
+
+  function togglePanel(panel: 'sidebar' | 'inspector') {
+    setMobilePanel((prev) => (prev === panel ? null : panel));
+  }
+
   return (
     <div className="app-shell">
       <header className="app-shell__toolbar">{toolbar}</header>
-      <aside className="app-shell__sidebar">{sidebar}</aside>
+      <aside className={`app-shell__sidebar${mobilePanel === 'sidebar' ? ' is-open' : ''}`}>{sidebar}</aside>
       <main className="app-shell__main">{children}</main>
-      <aside className="app-shell__inspector">{inspector}</aside>
+      <aside className={`app-shell__inspector${mobilePanel === 'inspector' ? ' is-open' : ''}`}>{inspector}</aside>
       <footer className="app-shell__statusbar">{statusbar}</footer>
+
+      {/* Mobile toggle buttons — visible only on narrow screens via CSS */}
+      <button
+        className="mobile-panel-toggle mobile-panel-toggle--left"
+        aria-label="Toggle shape palette"
+        onClick={() => togglePanel('sidebar')}
+      >
+        <svg width="20" height="20" viewBox="0 0 20 20" fill="none" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round">
+          {mobilePanel === 'sidebar'
+            ? <path d="M6 6l8 8M14 6l-8 8" />
+            : <><rect x="2" y="3" width="16" height="14" rx="2" /><path d="M8 3v14" /></>
+          }
+        </svg>
+      </button>
+      <button
+        className="mobile-panel-toggle mobile-panel-toggle--right"
+        aria-label="Toggle inspector"
+        onClick={() => togglePanel('inspector')}
+      >
+        <svg width="20" height="20" viewBox="0 0 20 20" fill="none" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round">
+          {mobilePanel === 'inspector'
+            ? <path d="M6 6l8 8M14 6l-8 8" />
+            : <><rect x="2" y="3" width="16" height="14" rx="2" /><path d="M12 3v14" /></>
+          }
+        </svg>
+      </button>
+
+      {/* Backdrop to close panel when tapping canvas area */}
+      {mobilePanel && (
+        <div className="mobile-panel-backdrop" onClick={() => setMobilePanel(null)} />
+      )}
     </div>
   );
 }
\ No newline at end of file
diff --git a/src/styles/globals.css b/src/styles/globals.css
index 224ae8a..561181d 100644
--- a/src/styles/globals.css
+++ b/src/styles/globals.css
@@ -1137,13 +1137,80 @@ select:focus-visible {
     gap: 8px;
     padding: 8px;
   }
+
+  /* Panels become fixed overlays, hidden by default */
   .app-shell__sidebar,
   .app-shell__inspector {
-    display: none;
+    position: fixed;
+    top: 0;
+    bottom: 0;
+    width: min(300px, 80vw);
+    z-index: 200;
+    overflow-y: auto;
+    transition: transform 0.25s ease;
+    padding: 12px;
+    box-shadow: 0 0 40px rgba(0, 0, 0, 0.6);
+    background:
+      linear-gradient(168deg, rgba(255, 255, 255, 0.04) 0%, transparent 40%),
+      rgba(15, 23, 42, 0.95);
+  }
+  .app-shell__sidebar {
+    left: 0;
+    transform: translateX(-100%);
+  }
+  .app-shell__sidebar.is-open {
+    transform: translateX(0);
+  }
+  .app-shell__inspector {
+    right: 0;
+    transform: translateX(100%);
+  }
+  .app-shell__inspector.is-open {
+    transform: translateX(0);
   }
+
   .app-shell__main {
     min-height: 50vh;
   }
+
+  /* Backdrop */
+  .mobile-panel-backdrop {
+    position: fixed;
+    inset: 0;
+    z-index: 199;
+    background: rgba(0, 0, 0, 0.4);
+  }
+
+  /* Toggle buttons */
+  .mobile-panel-toggle {
+    display: flex;
+    position: fixed;
+    bottom: 56px;
+    z-index: 201;
+    align-items: center;
+    justify-content: center;
+    width: 40px;
+    height: 40px;
+    border: 1px solid rgba(51, 65, 85, 0.6);
+    border-radius: 12px;
+    background: rgba(15, 23, 42, 0.85);
+    -webkit-backdrop-filter: blur(16px);
+    backdrop-filter: blur(16px);
+    color: rgba(226, 232, 240, 0.9);
+    cursor: pointer;
+    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
+  }
+  .mobile-panel-toggle--left  { left: 12px; }
+  .mobile-panel-toggle--right { right: 12px; }
+  .mobile-panel-toggle:active {
+    background: rgba(15, 23, 42, 1);
+  }
+}
+
+/* Hide toggle buttons on desktop */
+@media (min-width: 1101px) {
+  .mobile-panel-toggle { display: none; }
+  .mobile-panel-backdrop { display: none; }
 }
 
 @media (max-width: 640px) {