[Accessibility] nav pills tabs : The focus on active link is not visible

Created by: cfagno

On tabs with pills the focus on an active link is not visible (see https://v5.getbootstrap.com/docs/5.0/components/navs/) :

But on link button the focus is visible (see https://v5.getbootstrap.com/docs/5.0/components/buttons/) :

There is no focus style visible on Firefox browser for this active link, so we don't see the focus (we lose where we are).

To be accessible the focus on an active link must be visible (see success criterion 2.4.7 : https://www.w3.org/TR/WCAG21/#focus-visible).