问题

In this reference

At the bottom of the description,

They state that the ::selection selector can use the outline property, but I haven't been able to get this to work.

How do I affect outline with this selector properly?

回答1:

An important note from the Mozilla Developer Network:

The ::selection pseudo-element currently isn't in any CSS module on the standard track. It should not be used in production environments.

Which browser supports which properties on this pseudo-element is largely irrelevant today. You'll likely not get a consistent cross-browser experience, so you're probably better of avoiding the fringe details and stick to what each browser supports.

When ::selection was in the Selectors Specification (December 2005), we would read:

These are the CSS properties that apply to ::selection pseudo-elements: color, background, cursor (optional), outline (optional). The computed value of the 'background-image' property on ::selection may be ignored.

The color and background-color properties appear to be the best supported since they were the only non-optional values. Some browsers even support text-shadow, though it was not listed in the Specification.

I would avoid trying to achieve support for anything else cross-browser. Ultimately, keep in mind that non-standard features like this could up and vanish in the future. So don't get too attached to it.

Implementation and Support Details