Index: frontend/src/components/theme-toggle.tsx
===================================================================
--- frontend/src/components/theme-toggle.tsx	(revision b8093a091d45f33bab33deb8ff2fffc4734972c0)
+++ frontend/src/components/theme-toggle.tsx	(revision b8093a091d45f33bab33deb8ff2fffc4734972c0)
@@ -0,0 +1,37 @@
+"use client";
+
+import { Moon, Sun } from "lucide-react";
+import { useTheme } from "next-themes";
+import { useEffect, useState } from "react";
+
+export function ThemeToggle() {
+  const [mounted, setMounted] = useState(false);
+  const { theme, setTheme } = useTheme();
+
+  // Avoid hydration mismatch
+  useEffect(() => {
+    setMounted(true);
+  }, []);
+
+  if (!mounted) {
+    return (
+      <button className="p-2 rounded-md hover:bg-accent">
+        <Sun className="h-5 w-5" />
+      </button>
+    );
+  }
+
+  return (
+    <button
+      onClick={() => setTheme(theme === "dark" ? "light" : "dark")}
+      className="p-2 rounded-md hover:bg-accent transition-colors"
+      aria-label="Toggle theme"
+    >
+      {theme === "dark" ? (
+        <Sun className="h-5 w-5" />
+      ) : (
+        <Moon className="h-5 w-5" />
+      )}
+    </button>
+  );
+}