--- a/browser/themes/shared/tabs.inc.css
+++ b/browser/themes/shared/tabs.inc.css
@@ -795,21 +795,16 @@
   display: block;
   margin-inline-end: 0;
 }
 
 .all-tabs-item[selected] {
   box-shadow: inset 4px 0 var(--blue-40);
 }
 
-.all-tabs-button,
-.all-tabs-secondary-button {
-  background-color: transparent !important;
-}
-
 .all-tabs-secondary-button > label {
   display: none;
   margin: 0 5.5px;
 }
 
 .all-tabs-secondary-button[soundplaying] {
   list-style-image: url(chrome://browser/skin/tabbrowser/tab-audio-playing.svg);
 }