.sb-csv-export:before, .s-btn.sb-csv-export span {
    background-image: url("images/file-xls.png?1");
    background-size: 16px 16px;
}
.s-btn.sb-csv-export span {
    padding: 0 0 0 16px;
    width: 0;
    overflow: hidden;
}
img.export-list-demo {
    width: 16px;
    height: 16px;
}