button{
    outline: none;
    cursor: pointer;
    display: block;
    position: relative;
    text-align: center;
    padding: .5em 0;
    border: none;
    color: #FFF;
    background-color: transparent;
    font-family: serif;
    font-size: 32px;
    font-weight: 700;
    font-style: italic;
    text-transform: lowercase;
    text-shadow: 2px 2px rgba(0,0,0,.5);
    line-height: 1;
    transition: all .2s ease;
}

button:before{
    content: "";
    display: block;
    height: 100%;
    width: 180%;
    background-color: #4a5c4a;
    position: absolute;
    z-index: -1;
    left: -90%;
    top: 0;
    transition: all .3s ease;
}

button:hover:before,
button:focus:before{
    left: -40%;
}