diff --git a/index.html b/index.html
index 48cd2fc..58d5cfa 100644
--- a/index.html
+++ b/index.html
@@ -1,7 +1,16 @@
 <!doctype html>
-<html lang="zh-CN">
+<html lang="zh-CN" data-theme="dark">
   <head>
     <meta charset="UTF-8" />
+    <script>
+      (function () {
+        var key = 'memind-theme';
+        var stored = localStorage.getItem(key);
+        var theme = stored === 'light' || stored === 'dark' ? stored : 'dark';
+        document.documentElement.dataset.theme = theme;
+        document.documentElement.style.colorScheme = theme;
+      })();
+    </script>
     <meta
       name="viewport"
       content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no, viewport-fit=cover"
diff --git a/public/oa-drive/app.js b/public/oa-drive/app.js
index 6cb3d94..20a337c 100644
--- a/public/oa-drive/app.js
+++ b/public/oa-drive/app.js
@@ -5,7 +5,8 @@
 
   function getStoredTheme() {
     const stored = localStorage.getItem(THEME_STORAGE_KEY);
-    return stored === 'dark' ? 'dark' : 'light';
+    if (stored === 'dark' || stored === 'light') return stored;
+    return 'dark';
   }
 
   function applyTheme(theme) {
diff --git a/src/utils/theme.ts b/src/utils/theme.ts
index 1fa055a..6378521 100644
--- a/src/utils/theme.ts
+++ b/src/utils/theme.ts
@@ -4,7 +4,8 @@ export const THEME_STORAGE_KEY = 'memind-theme';
 
 export function getStoredTheme(): MemindTheme {
   const stored = localStorage.getItem(THEME_STORAGE_KEY);
-  return stored === 'dark' ? 'dark' : 'light';
+  if (stored === 'dark' || stored === 'light') return stored;
+  return 'dark';
 }
 
 export function applyTheme(theme: MemindTheme) {
