title: How to fix W3C CSS validation error - "Value Error Unknown Dimension" when using rem?
body: <p>According to <a href="http://caniuse.com/#feat=rem" rel="nofollow">http://caniuse.com/#feat=rem</a> <code>rem</code> is a valid unit for CSS3. Why do I get so many validation errors from <a href="http://www.css-validator.org/validator" rel="nofollow">http://www.css-validator.org/validator</a>?</p>