This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
By default, no style is applied. You can use this pseudo-class to customize the appearance of the submit button when there are invalid form fields.
Not part of any standard.
BCD tables only load in the browser