.block-heng-feng-youtube-video .video-frame {
    position: relative;
    padding-top: 56.25%; /* 16:9 Aspect Ratio */
    height: 0;
}

.block-heng-feng-youtube-video .video-frame iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}