CSS HTML Validator: The All-In-One HTML, XHTML, CSS, Link, SEO, and Accessibility Checker
CSS Validator Software
Need a CSS Validator? — Try CSS HTML Validator
Having problems with CSS? CSS HTML Validator for Windows (formerly CSE HTML Validator) not only thoroughly checks HTML syntax, but also checks CSS syntax. That means it's not only an HTML validator, but also a CSS validator (and it checks a lot more than that too).
CSS HTML Validator runs on your own computer so it protects your privacy and is super-fast. More:
Supports CSS3 with preliminary support for CSS4 (constantly updated)
Checks inline styles (the style attribute)
Checks internal style sheets (the content of the style element)
To check a document, simply open your document (a CSS file or HTML file containing CSS) in the program, press F6, and your document is checked with the results displayed at the bottom. It's that simple!