Update "Does CSS need to validate on pages?"

[Jefferydo]

"No. CSS won't interfere with the way assistive technologies understand content on a page. However, it is still encourage to do so."

The thing is, CSS validation can catch syntax errors and missing foreground/background colours. Properly-working CSS in required for a bunch of success criteria.

Finding errors inside media queries for other viewports is pretty handy, since (assuming they're visible) you'd only otherwise spot the errors if you test a different viewport at the problem view.

Edit: CSS validation will point out missing foreground/background colours (see Failure F24).

IDRC's old achecker tool provides CSS validation results along with the a11y errors, warnings, and HTML validation. Its CSS validation is currently down.