a further improvement

#main-content:focus {
    outline: 0;
}

This is one of the few situations in which it is acceptable to remove the outline from an element. The main content is not focusable in itself, so it doesn't really need a focus ring. The page jump when users click on the skip link should be enough of a visual indication that something happened.

At this point, our website is a lot more keyboard friendly than it used to be. That's it for now!