diff --git a/browser/background.js b/browser/background.js
index b79c94e2a..dbe664c2a 100644
--- a/browser/background.js
+++ b/browser/background.js
@@ -14,7 +14,7 @@ browser.webRequest.onHeadersReceived.addListener(({ responseHeaders, url }) => {
         else
             responseHeaders.push({
                 name: "content-type",
-                value: "text/json"
+                value: "text/css"
             });
     }