WCAG: No visual cue for focus state on text and bg color pickers

[Simon-Dirks]

This is from an external accessibility audit of our Mirador 3 install (WCAG 2.2 AA).

WCAG 2.4.7: Ensure each item receiving focus has a visible indicator (see https://www.w3.org/WAI/WCAG21/Understanding/focus-visible.html)
Currently, selecting a text or background color does not change the (visual) focus state of the buttons. Tested on Firefox on Mac.