.btn-simple {
    display: inline-block;
    border: 1px solid #e4e4e4;
    padding: 10px 40px;
    background: #f6f6f6;
    color: #666;
    overflow: hidden;
    margin-right: 20px;
    margin-bottom: 20px;
    width: 290px;
}
.div-box > a:nth-child(4n) {
    margin-right: 0;
}