<div class="video-responsive">     <iframe width="420" height="315" src="/" frameborder="0" allowfullscreen></iframe> </div>

.video-responsive{     overflow:hidden;     padding-bottom:56.25%;     position:relative;     height:0; } .video-responsive iframe{     left:0;     top:0;     height:100%;     width:100%;     position:absolute; }