.dd-arrow select {
    -webkit-appearance: none;
    -moz-appearance: none;
    background: url(../images/dd_arrow.png) no-repeat right #fff;
    background-position: 90%;
    background-position: calc(100% - 10px) 12px;
    background-position: -webkit-calc(100% - 10px) 12px;
    background-position: -moz-calc(100% - 10px) 12px;
}