.ad-desktop {
    display: block;
    text-align: center;
    margin: 10px 0;
}

.ad-mobile {
    display: none;
    text-align: center;
    margin: 10px 0;
}

@media (max-width: 768px) {
    .ad-desktop {
        display: none;
    }

    .ad-mobile {
        display: block;
    }
}