--- a/browser/themes/linux/browser.css
+++ b/browser/themes/linux/browser.css
@@ -722,16 +722,17 @@ menuitem.bookmark-item {
 
 #urlbar-zoom-button {
   -moz-appearance: none;
   margin: 0 3px;
   font-size: .8em;
   padding: 0 8px;
   border-radius: 1em;
   background-color: hsla(0,0%,0%,.05);
+  color: inherit;
   border: 1px solid ThreeDLightShadow;
 }
 
 #urlbar-zoom-button[animate="true"] {
   animation-name: urlbar-zoom-reset-pulse;
   animation-duration: 250ms;
 }
 

--- a/browser/themes/osx/browser.css
+++ b/browser/themes/osx/browser.css
@@ -1673,17 +1673,17 @@ toolbar .toolbarbutton-1 > .toolbarbutto
 }
 
 #urlbar-zoom-button {
   margin: 0 3px;
   font-size: .8em;
   padding: 0 8px;
   border-radius: 1em;
   background-color: hsla(0,0%,0%,.05);
-  border: 1px solid hsla(0,0%,0%,.1);
+  border: 1px solid ThreeDLightShadow;
 }
 
 #urlbar-zoom-button[animate="true"] {
   animation-name: urlbar-zoom-reset-pulse;
   animation-duration: 250ms;
 }
 
 #urlbar-zoom-button:hover {

--- a/browser/themes/windows/browser.css
+++ b/browser/themes/windows/browser.css
@@ -1388,16 +1388,17 @@ html|*.urlbar-input:-moz-lwtheme::placeh
 
 #urlbar-zoom-button {
   -moz-appearance: none;
   margin: 0 3px;
   font-size: .8em;
   padding: 0 8px;
   border-radius: 1em;
   background-color: hsla(0,0%,0%,.05);
+  color: inherit;
   border: 1px solid ThreeDLightShadow;
 }
 
 #urlbar-zoom-button[animate="true"] {
   animation-name: urlbar-zoom-reset-pulse;
   animation-duration: 250ms;
 }