Other than the obvious "to make sure I've got the syntax right", I don't see the point. I've just gone through lengths to make sure "non-standard" statements in my CSS files passed the W3C CSS validation. Then I came across some interesting articles on this issue.

One interesting example is the opacity rule. Although it's valid CSS3, some browsers (*cough* IE *cough*) don't support it as they should. Forcing me to do this...

Code: Select all

opacity: .9;  filter: progid:DXImageTransform.Microsoft.Alpha(style=0,opacity=90);

But why should I work around to hide the 'filter' rule when it's simply ignored by other browsers?
Why should the user be forced to download an additional stylesheet?
Why should I separate my code for different browsers when the idea of validation is that your code can be supported by most browsers?

I see the benefits of validating you HTML, but can someone explain why I should bother validating my CSS?