.btn-back {
    width: 50px;
    height: 50px;
    border-radius: 100%;
    line-height: 50px;
    text-align: center;
    vertical-align: middle;
    display: inline-block;
    z-index: 100;
    background-color: #ff6600;
    color: white;
    position: absolute;
    left: 30px;
    bottom: 15px;
    box-shadow: 0px 3px 5px rgba(0, 0, 0, 0.25);
}

    .btn-back:hover, .btn-back:focus, btn-back:active, btn-back:visited {
        color: white;
        background-color: #c14e01;
        cursor: pointer;
    }

.fa-arrow-left {
    font-size: 25px;
}