CSS attr() function
<div class="likebutton" data-likes="1">Like</div>
.likebutton{
width:100px;
border:1px solid blue;
}
.likebutton:before{
color: #FFFFFF;
content: attr(data-likes);
background:blue;
display: inline-block;
padding: 15px;
margin-right: 15px;
}