body {
    /* these don't matter: */
    margin: 0;
    padding: 0;
    }
    .full-window-height {
    height: 100vh; /* ONLY if you want the video to fill the entire browser window. Support: http://caniuse.com/#search=vh */
    }
    .video-bg {
    position: relative; /* contain the abs-pos <video> */
    width: 100%;
    overflow: hidden; /* prevent scrollbars */
    /* these below don't matter: */
    /*padding: 10% 0; */
    text-align: center;
    font: bold 40px/1.2 sans-serif;
    
    }
    .video-bg video {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%); /* keep centered in parent */
    z-index: -1; /* keep video behind other content */
    min-width: 100%; /* always cover horizontal */
    min-height: 100%; /* always cover vertical */
  
    }
    h1 {
    /* these don't matter: */
    color: white;
    text-shadow: 2px 2px 10px black;
    }