--- a/devtools/client/themes/animation.css
+++ b/devtools/client/themes/animation.css
@@ -519,16 +519,17 @@ select.playback-rate-selector.devtools-b
 }
 
 .keyframes-graph.transform .keyframes-graph-path path {
   fill: var(--yellow-50);
   stroke: var(--yellow-60);
 }
 
 .keyframes-graph-path .color-path path {
+  fill-opacity: 1;
   stroke: none;
 }
 
 .keyframes-graph .keyframes-graph-path .hint path {
   fill: none;
   stroke-linecap: round;
   stroke-opacity: 0;
 }