HTML Checker upgraded to W3C Validator Nu 20.3

We've just upgraded our HTML validation servers to the latest version of the W3C validator, 20.3, which was released today and includes many changes in the validation rules, so you may want to re-check your sites to get the most up-to-date results.

This release provides a number of improvements in ARIA role checking and in CSS checking, as well as support for checking a number of HTML features that weren’t supported previously:

• Disallow accept-charset values other than UTF-8
• Disallow object[typemustmatch]
• Allow SVG feDropShadow element (from Filter Effects spec)
• Allow loading attribute for the img element (lazy loading)
• Allow rel=modulepreload for the link element
• Allow integrity attribute on link[rel=preload|modulepreload]
• Allow integrity attribute on script[type=module]
• Allow autofocus as a global attribute
• Allow inputmode as a global attribute
• Allow nonce as a global attribute
• Allow allow-downloads in iframe[sandbox]
• Allow heading content within legend element
• Allow negated media features in media and sizes attributes
• Align autocomplete checking with current spec
• CSS: Improve support for color values
• ARIA: Allow implicit roles to satisfy owned-by requirements
• ARIA: Add proper ARIA checking for the math element
• ARIA: Align all role checking with current HTML-ARIA spec

Time to re-check your sites!

As usual, it's recommended to re-check your sites after the validation servers have been upgraded, to get the most up-to-date results. Remember that you can schedule your reports to run periodically, so you don't have to do that manually every time.