Rendere responsive i widget di youtube

Ho trovato questo link molto utile per risolvere il problema del responsive sui video embed di youtube.

http://www.kuma.cloud/blog/incorporare-youtube-in-un-sito-con-responsiv…

<div class="rwd-video">
    <iframe src="//www.youtube.com/embed/-lmlmt1Omew?rel=0" allowfullscreen="" frameborder="0" height="315" width="560">
    </iframe>
</div>

.rwd-video {
    height: 0;
    overflow: hidden;
    padding-bottom: 56.25%;
    padding-top: 30px;
    position: relative;
}
.rwd-video iframe,
.rwd-video object,
.rwd-video embed {
    height: 100%;
    left: 0;
    position: absolute;
    top: 0;
    width: 100%;
}