Validating CSS
 

When validating udm-style.php with W3C, I get the following errors. How can I get these items validated?

19 Unknown pseudo-element or pseudo-class :root
20 Unknown pseudo-element or pseudo-class :root
55 Unknown pseudo-element or pseudo-class %s
56 Unknown pseudo-element or pseudo-class %s
57 Value Error : min-width Property min-width doesn't exist : 0
58 Value Error : min-width Property min-width doesn't exist : 0
60 .udm .udmC Parse Error - opacity=0)