问题
I am using to check my CSS http://jigsaw.w3.org/css-validator but I get error for -webkit-border-radius, -moz-border-radius and border-radius. I know that this site test for v2.1 and all these border-radius is from v3. So why they don't use CSS v3 as testing? Or CSS v3 should't be used?
回答1:
They do, you just need to select the profile under More Options. The default is CSS level 2.1 as that's the most complete and final standard as of now. CSS level 3 is still in its early drafting stages — meaning any part of the spec can change drastically — and even the validator may be wrong sometimes, so it's not made default yet.
Bear in mind that vendor-prefixed styles will never validate as they are non-standard, but as Juhana says you can at the very least have them trigger warnings to allow your CSS to validate tentatively.
来源：https://stackoverflow.com/questions/7041008/css-border-radius-validation-errors