HTML Checking for Large Sites

Rocket Validator automatically checks your pages on the W3C Validator.

CSS: “filter”: "X" is not a “filter” value.

The specified CSS filter is not a standard one, and may only work in some browsers.

Check out the Filter Effects W3C Working Draft

Related W3C validator issues

When was the last time you validated your whole site?

Keep your sites healthy checking for A11Y/HTML issues on an automated schedule.