diff --git a/src/browser/themes/shared/zen-browser-shared.css b/src/browser/themes/shared/zen-browser-shared.css
index 704eaba0d..7b5ccf2dc 100644
--- a/src/browser/themes/shared/zen-browser-shared.css
+++ b/src/browser/themes/shared/zen-browser-shared.css
@@ -322,6 +322,10 @@ toolbarbutton#scrollbutton-up {
   align-items: center;
 }
 
+.tabbrowser-tab[pending]:not(:hover) {
+  opacity: 0.5;
+}
+
 .tabbrowser-tab[hidden="true"] {
   display: none !important;
 }