diff --git a/src/index.html b/src/index.html
index e5c9d1ea..c67cc8fa 100644
--- a/src/index.html
+++ b/src/index.html
@@ -1,5 +1,5 @@
 ﻿<!DOCTYPE html>
-<html lang="en">
+<html class="__OS__">
 <head>
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1">
