diff --git a/parent-vite.config.js b/parent-vite.config.js
index bc6bcbf4f33cd1de857fe07d3e0433dc2d65a892..1ca929f7bbabba62e5ad472c0e1de448a14953c8 100644
--- a/parent-vite.config.js
+++ b/parent-vite.config.js
@@ -15,6 +15,6 @@ module.exports = defineConfig({
         assetsInlineLimit: 0,
     },
     define: {
-        cssFileName: cssLink.replace(/assets\//, ""),
+        CSS_FILE_NAME: cssLink.replace(/assets\//, ""),
     }
 });
diff --git a/src/parent.ts b/src/parent.ts
index 77d5b41db37d8c148567b1eb947bdaef1ba92d4a..511ddebd3011f95f38fbd9e1415b05cf50a90613 100644
--- a/src/parent.ts
+++ b/src/parent.ts
@@ -46,7 +46,7 @@ function renderStartButton() {
 function loadCSS() {
     const linkElement = document.createElement("link") as HTMLLinkElement;
     linkElement.rel = "stylesheet";
-    const urlFixed = new URL("cssFileName", parentRootHost);
+    const urlFixed = new URL("CSS_FILE_NAME", parentRootHost);
     linkElement.href = urlFixed.href;
     document.head.appendChild(linkElement);
 }
diff --git a/vite.config.js b/vite.config.js
index b3b82b3dd032856ba0c4b1e5cdbec3fcbe293bea..b7e25214b4cd63430346ae89cb5e2e48cfd7fea5 100644
--- a/vite.config.js
+++ b/vite.config.js
@@ -6,7 +6,7 @@ module.exports = defineConfig(({ command }) => {
         return {
             // dev specific config
             define: {
-                cssFileName: JSON.stringify("parent-style.css"),
+                CSS_FILE_NAME: JSON.stringify("parent-style.css"),
             },
         };
     } else {