.shop-box{
    width: 266px;
    margin: 0 auto;
}

.shop-box iframe{
    width: 100%;
    height: 2749px; /* 12 items */
}

@media (min-width: 506px)
{
    .shop-box {
        width: 506px;
    }
    .shop-box iframe {
        height: 1417px; /* 6 items */
    }
}

@media (min-width: 746px)
{
    .shop-box { 
        width: 746px;
    }
}