You can validate any HTML5 or pre-HTML5 web browser for CSS3 support using various online tools. For CSS3, there are two different levels of validation to consider: CSS3 selector logic and CSS3 property application.
CSS3 selector logic confirms how well the browser understands the new CSS3 selectors, such as selecting an element by a partial attribute value, by its nth-child or nth-type pseudo-class, by input status, by user selection, and so on.
CSS3 property application pertains to how well the browser understands the new properties that can be applied, such as multiple background-image support, custom fonts, custom image borders, and so on.
Here are some of the online tools that you can use to validate ...