No visible focus indicator on tabs

[matteason]

Version

@nuxt/ui: 2.8.1

Reproduction Link

https://ui.nuxt.com/navigation/tabs

Steps to reproduce

1. Use the tab key to navigate to the tabs on the screen
2. Observe that they have no visible focus state

What is Expected?

Like, other controls, tabs should have a visible focus state to indicate they're currently focussed. For example, buttons have a green ring:

What is actually happening?

There's no visible indication when the a tab has focus. This is an accessibility issue and apps using this component would fail WCAG 2.4.7 (Focus Visible)