The required pseudo-class

The required pseudo-class specifies the style of the input that has the required attribute, i.e. this pseudo-class applies to required inputs.

Syntax

selector:required {}

Let's give the required input a blue background:

<form>
	<p>
		<label>Enter number</label>
		<input type="number" required>
	</p>
	<p>
		<label>Enter text</label>
		<input type="text">
	</p>
</form>

input:required {
	background-color: #C2DDFD;
}