To style [Python-Markdown Tabbed Extension](https://facelessuser.github.io/pymdown-extensions/extensions/tabbed/).

> **♿ Accessibility Extras**
>
> 1. Focus on tab container. Verify it **has** focus outline.
> 2. While focused on tab container, press <kbd>←</kbd> and <kbd>→</kbd>. Verify tab switches.
> 3. While on tab 1, focus on input field within. Verify tab container has **no** focus outline.