BugFix for regex

lib/views/admin/customize.html

@@ -430,7 +430,7 @@ window.addEventListener('load', (event) => {
       // selected value
       var val = event.target.value
       // replace css url
-      highlightJsCssDOM.href = highlightJsCssDOM.href.replace(/[^/]+/.css$/, `${val}.css`);
+      highlightJsCssDOM.href = highlightJsCssDOM.href.replace(/[^/]+\.css$/, `${val}.css`);
       // reload highlight.js of demo code
       hljs.highlightBlock(highlightJsCssDOM);
     }