.responsive-iframe {
    position: relative;
    padding-bottom: 56.25%;
        /*aspect ratio 16:9 */
    height: 0; 
    overflow: hidden;
}
.responsive-iframe iframe {
    width: 100%;
    height: 100%;
    position: absolute;
    left: 0;
    top: 0;
}

min-width:100%;
max-width:100%;