You can change the pseudo-element based on hover of the parent:
#button:before {
background-color: blue;
content: "";
display: block;
height: 25px;
width: 25px;
}
#button:hover:before {
background-color: red;
}
#button { display: block;
height: 25px;
margin: 0 10px;
padding: 10px;
text-indent: 20px;
width: 12%;}
#button:before { background-color: blue;
content: "";
display: block;
height: 25px;
width: 25px;}
#button:hover:before { background-color: red;}
<div id="button">Button</div>