feat(css): Remove border radius from WebKit's scrollbars (#4278)

app/javascript/styles/components.scss

@@ -3711,6 +3711,10 @@ button.icon-button.active i.fa-retweet {
   }
 }
 
+::-webkit-scrollbar-thumb {
+  border-radius: 0;
+}
+
 noscript {
   text-align: center;