diff --git a/mapper/src/App.css b/mapper/src/App.css
index c64c6c8..a881e55 100644
--- a/mapper/src/App.css
+++ b/mapper/src/App.css
@@ -140,9 +140,10 @@ h2 {
 	place-content: center;
 }
 
-/* Fix for Firefox Mobile rendering a black background on checked state */
+/* Fix for Firefox Mobile rendering a black background on checked state,
+   especially when extensions like Dark Reader are active. */
 .submenu-checkbox-label input[type="checkbox"]:checked {
-	background-color: transparent;
+	background-color: transparent !important;
 }
 
 .submenu-checkbox-label input[type="checkbox"]::before {