.wp-ads-slider {
    position: relative;
    width: 100%;
    max-width: 100%;
    overflow: hidden;
}

.wp-ads-slider a {
    display: none;
    width: 100%;
    height: 100%;
    text-align: center;
}

.wp-ads-slider a:first-child {
    display: block;
}

.wp-ads-slider img {
    width: 100%;
    height: auto;
    max-height: 300px;          /* OPTIONAL: limit banner height */
    object-fit: contain;        /* 🔥 MAIN FIX */
    object-position: center;
}