.backBtn {
    color: #fff !important;
    background: #31AB2A;
    display: inline-block;
    font-family: chewy, verdana, arial;
    font-size: 26px;
    height: 40px;
    line-height: 40px;
    padding: 0 15px;
    position: relative;
    text-decoration: none;
    transition: all 100ms ease-out;
    white-space: nowrap;
    z-index: 1;
}
.backBtn:hover,
.backBtn:focus {
    background: #fff;
    color: #31AB2A !important;
    text-decoration: none;
}
.backBtn:hover span {
    background-position: 0 -39px;
}
    .backBtn::after {
        border-bottom: 20px solid transparent;
        border-right: 15px solid #31AB2A;
        border-top: 20px solid transparent;
        content: "";
        display: block;
        left: -15px;
        height: 0;
        position: absolute;
        top: 0;
        transition: all 100ms ease-out;
        width: 0;
    }
    .backBtn:hover::after,
    .backBtn:focus::after {
        border-right: 15px solid #fff;
    }
.backBtn-eBook {
    z-index: 9999;
}