.wp-block-cover iframe.db-vimeo-background {
    z-index: 1;
    position: absolute;
    width: 100%;
    height: auto;
    aspect-ratio: 16/9;
}

@media (max-aspect-ratio: 16/9) {
    .wp-block-cover iframe.db-vimeo-background {
        width: auto;
        height: 100%;
    }
}