<div class="div_video">
<iframe src="//www.youtube.com/embed/t9nt1n4_pCQ?rel=0" frameborder="0" allowfullscreen class="video"></iframe>
</div>
<style>
.div_video {
position: relative;
width: 100%;
height: 0;
padding-bottom: 56.25%;
}
.video {
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
}
</style>
