When clicking to upvote a comment, the icon seems to retain focus resulting in a border around the icon (the bottom comment in the image below). This remains until I click elsewhere on the page or switch windows (at which point it looks like the top comment in the image below). This happens on multiple SE sites, and I'm not sure when it started. Previously, clicking the upvote icon would switch it from gray to blue, and no border would be present (or it would go away on it's own immediately).
System is Windows 10 with Chrome browser Version 68.0.3440.106 (Official Build) (64-bit)