--- a/browser/base/content/browser.css
+++ b/browser/base/content/browser.css
@@ -129,29 +129,32 @@ tabbrowser {
 
 .tabbrowser-tab:not([pinned]):not([fadein]) {
   max-width: 0.1px;
   min-width: 0.1px;
   visibility: hidden;
 }
 
 .tab-close-button,
+.tabbrowser-tab::after,
 .tab-background {
   /* Explicitly set the visibility to override the value (collapsed)
    * we inherit from #TabsToolbar[collapsed] upon opening a browser window. */
   visibility: visible;
 }
 
 .tab-close-button[fadein],
+.tabbrowser-tab[fadein]::after,
 .tab-background[fadein] {
   /* This transition is only wanted for opening tabs. */
   transition: visibility 0ms 25ms;
 }
 
 .tab-close-button:not([fadein]),
+.tabbrowser-tab:not([fadein])::after,
 .tab-background:not([fadein]) {
   visibility: hidden;
 }
 
 .tab-label:not([fadein]),
 .tab-throbber:not([fadein]),
 .tab-throbber-fallback:not([fadein]),
 .tab-icon-image:not([fadein]) {