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W3.CSS Validation


CSS Validation

The W3C CSS Validation Service can be used to check the correctness (validity) of W3.CSS.

The Validation Service was created by the W3C to help Web developers validate CSS.


Validation Warnings

The W3C CSS Validator checks for CSS1, CSS2, CSS3, and CSS4 properties.

 Some browsers use vendor extensions to simulate CSS3 and CSS4 properties.

Vendor extensions can create warnings in the W3 CSS validation prosess.


Vendor Extensions

W3.CSS uses vendor extensions to support older browsers.

Browser vendors are working to stop using prefixes in future browser versions.

Until then, some extensions will have to be used to make modern CSS work in all browsers.

Below is a list of the most common vendor extensions used:

ExtensionBrowser
-webkit-Chrome, Safari, Opera
-moz-Firefox
-o-Old Opera versions
-ms-Microsoft Edge and Internet Explorer