diff --git a/lib/setup/web-server.js b/lib/setup/web-server.js
index 7cc7186..1a89c49 100644
--- a/lib/setup/web-server.js
+++ b/lib/setup/web-server.js
@@ -67,7 +67,7 @@ export default async function setupWebServer(config = {
     setupQUnit();
   </script>`;
 
-    if (req.url === '../node_modules/qunit/qunit/qunit.css') {
+    if (['../node_modules/qunit/qunit/qunit.css', './node_modules/qunit/qunit/qunit.css', '/node_modules/qunit/qunit/qunit.css'].includes(req.url)) {
       res.writeHead(200, { 'Content-Type': 'text/css' });
       return res.end(cachedContent.QUnitCSS, 'utf-8');
     }