使用 :focus | 码农工具

​x
 
<!DOCTYPE html>
<html>
<head>
<style>
    input:focus
    {
        background-color:yellow;
    }
</style>
</head>
​
<body>
    <form action="demo-form.php" method="get">
    First name: <input type="text" name="fname"/><br>
    Last name:  <input type="text" name="lname"/><br>
    <input type="submit" value="Submit"/>
</form>
​
<p><b>Note:</b> IE8 supports the :focus pseudo-class only if a !DOCTYPE is specified.</p>
​
</body>
</html>
HTML