The visible outline drawn around the element that currently holds keyboard focus, marking where the next key press will land.
Don’t delete the focus ring, restyle it: a 2px accent outline with a little offset reads clearly without shouting.
The focus ring is the cursor for everyone not using a mouse. outline: none
with nothing in its place is the most common accessibility failure on the web:
it blinds keyboard and switch users to their own position. Reach for
:focus-visible, which shows the ring for keyboard navigation and hides it for
mouse clicks, so the two audiences stop fighting over the same pixels.