JSFiddle - React, Tailwind, and code Playground

HTML

<div id='button'>
    <span>Send Email</span>
</div>

CSS

#button {
    font-size: 1.4em;
    color: #333;
    background-color: #555;
    position: relative;
    padding:15px 40px 15px 120px;
    background-image: url('http://i55.tinypic.com/2agsutj.png');
    background-repeat: no-repeat;
    background-position:35px 10px;
    position: absolute;
    left: 40px;
    top: 5px;
}
#button:hover {
    color: #fff;
    cursor: pointer;
    background-position:35px -29px;
}