.responsive-iframe {
    position: relative;
    display: block;
    overflow: hidden;
    padding-top: 100%;
}

.responsive-iframe.is-16x9 {
    padding-top: 56.25%;
}

.responsive-iframe.is-4x3 {
    padding-top: 75%;
}

.responsive-iframe > iframe {
    position: absolute;
    top: 0;
    left: 0;
    height: 100% !important;
    width: 100%;
    border: 0;
}