Sarah Higley has some CSS tricks up her sleeve for dealing with High Contrast Mode on Windows, which I learned is referred to as WHCM.

Here’s the first trick:

[…] if the default CSS outline property doesn’t give you the visual effect you want [in WHCM] for focus states, there’s a very simple fix. Instead of overriding default browser focus styles with outline: none, make it transparent instead: outline 3px solid transparent.

That will essentially do nothing outside of WHCM, but in WHCM, it will be a thick white border, which is a strong, good visual focus style.

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