
The CSS :checked selector selects all checked elements like radio buttons, checkboxes, and <option> element.
Example1:
Changing the width and height for every checked element (for radio buttons, checkboxes):
<!DOCTYPE html>
<html>
<head>
<style>
input:checked {
height: 45px;
width: 45px;
}
</style>
</head>
<body>
<form action="">
<input type="radio" checked="checked" value="black" name="colours">Black<br>
<input type="radio" value="white" name="colours">White<br>
<input type="checkbox" checked="checked" value="dog"> I have a dog.<br>
<input type="checkbox" value="cat"> I have a cat.
</form>
</body>
</html>
Output:
Black
White
I have a dog.
I have a cat.
White
I have a dog.
I have a cat.
Example2:
Changing the width and height for every checked element (for the <option> element):
<!DOCTYPE html>
<html>
<head>
<style>
option:checked {
height: 150px;
width: 150px;
}
</style>
</head>
<body>
<select>
<option value="html">HTML</option>
<option value="css">CSS</option>
<option value="js">JavaScript</option>
<option value="jQ">jQuery</option>
</select>
</body>
</html>
Output:
Enjoy coding!