Responsive YouTube Embed

<style>
.embed-container {
    position: relative;
    padding-bottom: 56.25%;
    padding-top: 30px;
    height: 0;
    overflow: hidden;
    max-width: 100%;
    height: auto;
}
.embed-container iframe, .embed-container object, .embed-container embed {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}
</style>
<div class='embed-container'>
    <iframe src='http://www.youtube.com/embed/dQw4w9WgXcQ' frameborder='0' allowfullscreen></iframe>
</div>