--- a/browser/themes/linux/browser.css
+++ b/browser/themes/linux/browser.css
@@ -952,20 +952,23 @@ toolbaritem[cui-areatype="menu-panel"] >
   /* 16x16 icon with border-box sizing */
   width: 22px;
   height: 16px;
 }
 
 /* ::::: URL Bar Zoom Reset Button ::::: */
 @keyframes urlbar-zoom-reset-pulse {
   0% {
-  transform: scale(0);
+    transform: scale(0);
+  }
+  75% {
+    transform: scale(1.5);
   }
   100% {
-  transform: scale(1.5);
+    transform: scale(1.0);
   }
 }
 
 #urlbar-zoom-button {
   -moz-appearance: none;
   margin: 0 3px;
   font-size: .8em;
   padding: 0 8px;

--- a/browser/themes/osx/browser.css
+++ b/browser/themes/osx/browser.css
@@ -1662,18 +1662,21 @@ toolbar .toolbarbutton-1 > .toolbarbutto
   height: 16px;
 }
 
 /* ::::: URL Bar Zoom Reset Button ::::: */
 @keyframes urlbar-zoom-reset-pulse {
   0% {
     transform: scale(0);
   }
+  75% {
+    transform: scale(1.5);
+  }
   100% {
-    transform: scale(1.5);
+    transform: scale(1.0);
   }
 }
 
 #urlbar-zoom-button {
   margin: 0 3px;
   font-size: .8em;
   padding: 0 8px;
   border-radius: 1em;

--- a/browser/themes/windows/browser.css
+++ b/browser/themes/windows/browser.css
@@ -1384,20 +1384,23 @@ html|*.urlbar-input:-moz-lwtheme::-moz-p
   /* 16x16 icon with border-box sizing */
   width: 22px;
   height: 16px;
 }
 
 /* ::::: URL Bar Zoom Reset Button ::::: */
 @keyframes urlbar-zoom-reset-pulse {
   0% {
-  transform: scale(0);
+    transform: scale(0);
+  }
+  75% {
+    transform: scale(1.5);
   }
   100% {
-  transform: scale(1.5);
+    transform: scale(1.0);
   }
 }
 
 #urlbar-zoom-button {
   -moz-appearance: none;
   margin: 0 3px;
   font-size: .8em;
   padding: 0 8px;