Valid, invalid, and required definitions in html5

Comments: The emergence of HTML5 provides us with some attributes. This validation form content can be solved without writing js and regular expressions, the following describes the definition of css3 for valid, invalid, and required. The prompt only applies to advanced browsers:

Chrome
Firefox
Safari
IE9 +

Valid, invalid, and required Definitions

The Code is as follows:

The Code is as follows:
Input: required, input: valid, input: invalid {border: 0 none; outline: 0 none;-webkit-box-shadow: none;-moz-box-shadow: none; -ms-box-shadow: none;-o-box-shadow: none ;}

In the past, the verification form will use js and regular expressions to determine whether the entered content is correct, such as email verification.

The emergence of HTML5 provides us with some attributes. This validation form content can be solved without writing js and regular expressions.
: Required
Required. input cannot be empty.

: Valid
Valid: triggered when the entered content meets the requirements.

: Invalid
Invalid. This is triggered when the entered content does not meet the requirements.