diff --git a/src/generators/web/template.html b/src/generators/web/template.html
index fe6a5823..78fceb72 100644
--- a/src/generators/web/template.html
+++ b/src/generators/web/template.html
@@ -19,7 +19,7 @@
     href="https://fonts.googleapis.com/css2?family=IBM+Plex+Mono&family=Open+Sans:ital,wght@0,300..800;1,300..800" />
 
   <!-- Apply theme before paint to avoid Flash of Unstyled Content -->
-  <script>document.documentElement.setAttribute("data-theme", document.documentElement.style.colorScheme = localStorage.getItem("theme") || (matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light"));</script>
+  <script>(function(){var p=localStorage.getItem("theme");var t=(!p||p==="system")?(matchMedia("(prefers-color-scheme: dark)").matches?"dark":"light"):p;document.documentElement.setAttribute("data-theme",t);document.documentElement.style.colorScheme=t;})();</script>
   <script type="importmap">${importMap}</script>
   <script type="speculationrules">${speculationRules}</script>
 </head>