getButtonClass()function

The button styling variants (block, flex, status, plus button toggles). required

Solid styling: a strong fill of the tint colour with white text. Use it for the main action.

Plain styling: no fill or border until hover or focus.

Outline styling: like plain, but with a border until hover or focus.

Whether the button is the selected one in a group, such as a set of tabs.
- true sets aria-pressed (or aria-current on a link) and keeps the button's normal look.
- false also drops the fill until hover or focus, so the selected button stands out.
- undefined (the default) means the button is not part of a group.

Make the button appear smaller.

Fill the available width instead of sizing to content (buttons are content-width by default).

A space-separated className string combining all the resolved variant classes.