una/studio/template/css/options.css

div.bx-stg-mixes {
    position: relative;
    white-space: nowrap;
}
div.bx-stg-mixes div.bx-sm-cell {
    position: relative;
}
div.bx-stg-mixes div.bx-sm-cell.bx-sm-select {
    float: left;
    width: 50%;
}
div.bx-stg-mixes div.bx-sm-cell.bx-sm-new {
    float: right;
    width: 50%;

    text-align: right;
}

div.bx-stg-mixes div.bx-sm-cell select {
    width: auto;
}

div.bx-stg-mixes div.bx-sm-cell .bx-btn {
    display: inline-block;
    float: none;
    vertical-align: middle;
}