Can anyone tell me why button focus borders are rendered with a black dashed border by default in IE11 and with a blue solid border in Chrome? You can see this if you go to <http://angular-ui.github.io/> and tab over the Site/Code buttons with IE11 and Chrome.

I've tried various overrides like -webkit-appearance:none etc to no avail. Is this an AngularUI bug, or a browser quirk everybody knows about and have been working around that I'll need to special-case if I want the look to be uniform?