Use of outline:none leave no focus state styling in Windows +Edge with High Contrast Mode on.

Feedback summary

On Windows + Edge, with High Contrast Mode on (type left-shift+left-alt+PrintScreen to toggle it), there is no focus state styling for some controls in Paragon.

Improvements

In practice there is a better way to use outline: anywhere that we have an alternative to outline attribute for focus state styling: we should probably use outline: transparent instead of outline: none. This is because, transparent value gets mapped to a visible value in HC mode, and focus styling does its job.

Bugs

This affect may be specific to Edge on Windows.
Generally we use box-shadow for focus state styling, for two reasons: 1) it allows rounded corners (unlike outline, last time I checked), 2) it allow a gap between the focus state styling (2px box-shadow) and the thing being focused, which helps with WCAG 2.2: https://www.w3.org/TR/WCAG22/#focus-appearance (we're not required to conform to AAA-level WCAG Guidelines, but we do here so that's a bonus.

In Windows High Contrast Mode, box-shadows are removed and outline (if not None) is turned into a bright high-contrast color. But none value does not get mapped, so there may be no focus state styling in Window with High Contrast Mode on.

Search the Paragon component styles for outline:none and the associated box-shadow focus rules. Test affected controls in Windows Edge with High Contrast Mode enabled, then verify that focus remains visibly styled without regressing the existing rounded-corner and focus-gap behavior.