JSFiddle - React, Tailwind, and code Playground
HTML
<a href="#" class="botao"><span>Contrate agora</span><span></span></a>
CSS
.botao {
display: inline-block;
position: relative;
width:120px;
height:30px;
text-align:center;
text-decoration:none;
color:#FFF;
background: url(http://i.stack.imgur.com/5PWNy.png) repeat-x;
}
.botao span:first-child{
z-index:30;
position:absolute;
display:block;
left:0;right:0;margin:auto;
margin-top:5px;
}
.botao span:last-child{z-index:29;
position: absolute; z-index:0;
top: 0; left: 0; bottom: 0; right: 0;
background: url(http://i.stack.imgur.com/5PWNy.png) repeat-x;
background-position: 0px -50px;
opacity: 0;
-webkit-transition: opacity 0.5s;
-moz-transition: opacity 0.5s;
-o-transition: opacity 0.5s;
}
.botao:hover span {
opacity: 1;
}