Responsive Vimeo, Youtube video

fullscreen.html

<style>
    .embed-container {
        position: relative;
        padding-bottom: 56.25%;
        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='https://player.vimeo.com/video/11712103' frameborder='0' webkitAllowFullScreen mozallowfullscreen allowFullScreen></iframe>
</div>