Great video over at the Google Chrome Developers channel about the upcoming CSS Level 4
:focus-ring selector (draft). The focus is often removed for stylistic reasons when using the mouse, but then keyboard users also have no indication of where they are on the website.
:focus-ring solves that issue.
https://www.youtube.com/watch?v=ilj2P5-5CjI&index=1&list=PLNYkxOF6rcICWx0C9LVWWVqvHlYJyqw7g The video includes a shout out to this handy polyfill on Github. There are other videos about accessibility, also presented by Rob Dodson, available on the channel as well. Captions are available.