--- a/devtools/client/themes/animationinspector.css
+++ b/devtools/client/themes/animationinspector.css
@@ -334,20 +334,16 @@ body {
   border: 1px solid var(--timeline-border-color);
   /* Border-right is already handled by the gradient */
   border-width: 1px 0 1px 1px;
 
   /* The background color is set independently */
   background-color: var(--timeline-background-color);
 }
 
-.animation-timeline .animation .iterations.infinite {
-  border-right-width: 0;
-}
-
 .animation-timeline .animation .iterations.infinite::before,
 .animation-timeline .animation .iterations.infinite::after {
   content: "";
   position: absolute;
   top: 0;
   right: 0;
   width: 0;
   height: 0;