CSS pseudo class (lower) structure pseudo class \ UI pseudo class \ Dynamic pseudo class and other pseudo class valid check enable child required link visit, uivalid

CSS pseudo class (lower) structure pseudo class \ UI pseudo class \ Dynamic pseudo class and other pseudo class valid check enable child required link visit, uivalid

 

: Checked check takes effect

Html file

Css file

Hide selected items

: Default takes effect by default, rarely used

Css file

: Valid when valid is valid

: Invalid

Html file

Css file

If you have entered the correct number, it turns green.

: The required part takes effect.

Optional is not mandatory.

 

Html file

Css file

 

A: The link acts on the text between tags.

Input: focus

Switch the text input cursor. The input box changes color.