graff/themes/shop/js/tabs/tabs.css

.tabn {
    overflow: hidden;
    border: 1px solid #ccc;
    background-color: #f1f1f1;
}

.tabn button {
    background-color: inherit;
    float: left;
    border: none;
    outline: none;
    cursor: pointer;
    padding: 14px 16px;
    transition: 0.3s;
    font-size: 17px;
}

.tabn button:hover {
    background-color: #ddd;
}

.tabn button.active {
    background-color: #ccc;
}

.tabncontent {
    display: none;
    padding: 6px 12px;
    border: 1px solid #ccc;
    border-top: none;
}