btn-outline.active box shadows

Created by: mudrz

Bootstrap 4 beta 3

Related to active buttons issue @ysds https://github.com/twbs/bootstrap/issues/24760 Related pull request @mdo https://github.com/twbs/bootstrap/pull/25070

I agree to remove the focus box shadow from .active.

The focus outline(box shadow) should only be used to highlight the focused elements - only one >element per window has the focus at a time.

In beta 3 the .active box shadow button issue was fixed for regular buttons, but not for outline buttons. Additionally active outline buttons no longer change their text color when active https://codepen.io/anon/pen/vpmZZM?editors=1000#0