Change britness on hover
HTML
<a href="#">Button</a>
CSS
body {
margin: 0
}
a {
padding: 20px 40px;
background: green;
color: white;
text-decoration: none;
font-family: sans-serif;
font-size: 18px;
display: inline-block;
margin: 30px;
}
a:hover, a:active {
background-color: red;
}