.f13-youtube-container {
    width: 100%;
    position: relative;
    height: 0px;
    padding-bottom: 56.25%;
    margin-bottom: 10px;
}

.f13-youtube-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: 0;
}