:checked is a pseudo-class selector that's used to style the checked state of radio, checkbox or option elements:

				
					
:checked {

  background-color: hotpink;

}



/* Only style checked checkboxes */

input[type="checkbox"]:checked {

  padding-left: 1em;

}

				
			

Explicit styling unchecked elements

pseudo-class selector illustration for: Explicit styling unchecked elements

You can use the :not pseudo-class with :checked to explicit style unchecked elements. This can be useful if there are certain styles that you don't want to see applied to the checked state:

				
					
input:not(:checked) {

  opacity: 0.6;

}

				
			

Browser Support

Can I Use css-sel3? Data on support for the css-sel3 feature across the major browsers from caniuse.com.