JSFiddle - React, Tailwind, and code Playground

HTML

<div id="button"
<a href="#text" name="text">Send Email</a>
</div>

CSS

#button {
    display:block;
    width: 270px;
    height: 45px;
    font-size: 1.4em;
    background-color: #555;
    position: relative;
    
    padding-left: 45px;
    padding-top: 15px;    
}

#button a {
    text-decoration:none;
    color:#333;
    padding:5px;
    padding-left: 65px;
    background-image: url('http://i55.tinypic.com/2agsutj.png');
    background-repeat: no-repeat;
    background-position: 0px 0px;    
}

#button a:hover {
   background-position:0px -39px;
   color: #fff;
}

JavaScript

$(function() {
    $('#button').hover(function() {
        $('#button > .icon').css('background-position', '0px -39px');
    }, function() {
        $('#button > .icon').css('background-position', '0px 0px');
    });
});