diff --git a/src/services/style_setter/style_setter.js b/src/services/style_setter/style_setter.js
index a8b7e43e5..dd22b80e0 100644
--- a/src/services/style_setter/style_setter.js
+++ b/src/services/style_setter/style_setter.js
@@ -24,6 +24,11 @@ export const createStyleSheet = (id, priority = 1000) => {
       if (!CSS.supports?.('backdrop-filter', 'blur()')) {
         newRule = newRule.replace(/backdrop-filter:[^;]+;/g, '') // Remove backdrop-filter
       }
+
+      // firefox doesn't like invalid selectors
+      if (!CSS.supports?.('::-webkit') && newRule.startsWith('::-webkit')) {
+        return
+      }
       this.rules.push(
         newRule
           .replace(/var\(--shadowFilter\)[^;]*;/g, '') // Remove shadowFilter references