--- a/toolkit/content/aboutTelemetry.css
+++ b/toolkit/content/aboutTelemetry.css
@@ -75,17 +75,17 @@ body {
   background-image: url(chrome://global/skin/icons/arrow-dropdown-16.svg);
   background-position: right 8px center;
   background-repeat: no-repeat;
   -moz-context-properties: fill;
   fill: currentColor;
 }
 
 body[dir=rtl] .dropdown {
-  background-position: left 8px center;
+  background-position-x: left 8px;
 }
 
 #controls {
   display: flex;
   margin-top: 4px;
   justify-content: space-between;
 }