<style>

  .video-container {

    position: relative;

    padding-bottom: 56.25%; /* Set the aspect ratio of the video (e.g. 16:9) */

    height: 0;

    overflow: hidden;

  }

​

  .video-container iframe, .video-container embed, .video-container object {

    position: absolute;

    top: 0;

    left: 0;

    width: 100%;

    height: 100%;

  }

</style>

​

<div class="video-container">

  <iframe src="https://www.youtube.com/embed/your-video-id" frameborder="0" allowfullscreen></iframe>

</div>