Firefox (Nightly) on Android: tabs don't work: when clicking on a tab, the URL changes, there's a slight jump in content, but the new tab is not selected. Hope this helps
I have a vague feeling that tabs should be doable in pure CSS/HTML, but I might be thinking of menus (where the menu is a sub element of the button and thus visibility can depend on mouse position)
> Tabs should be managed by adding custom javascript code. All you need is to add the [aria-selected=true] attribute to the active tab.