diff --git a/en/index.html b/en/index.html
index 2a59980..1fd7074 100644
--- a/en/index.html
+++ b/en/index.html
@@ -2,7 +2,7 @@
 <html lang="en">
 <head>
 <meta charset="utf-8">
-<script>document.documentElement.classList.add("js")</script>
+<script>document.documentElement.classList.add("js");(function(m){if(m)document.documentElement.dataset.theme=m[1]})(document.cookie.match(/(?:^|; )interimm-theme=(light|dark)/))</script>
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <meta name="color-scheme" content="light dark">
 <title>Mars Map | InterImm</title>
diff --git a/index.html b/index.html
index f325de3..941e497 100644
--- a/index.html
+++ b/index.html
@@ -2,7 +2,7 @@
 <html lang="zh-CN">
 <head>
 <meta charset="utf-8">
-<script>document.documentElement.classList.add("js")</script>
+<script>document.documentElement.classList.add("js");(function(m){if(m)document.documentElement.dataset.theme=m[1]})(document.cookie.match(/(?:^|; )interimm-theme=(light|dark)/))</script>
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <meta name="color-scheme" content="light dark">
 <title>火星地图 | 星际移民中心</title>