.wvb-variation-buttons button {
    margin: 0 5px 5px 0;
    padding: 8px 15px;
    border: 1px solid #ccc;
    background: #f7f7f7;
    cursor: pointer;
    transition: all 0.2s;
}
.wvb-variation-buttons button.selected {
    border-color: #333;
    background: #333;
    color: #fff;
}