A question

<video id="background_video" autoplay loop muted>
<source src="" type="video/mp4">
</video>

<video_head>
</video_head>
<video_subhead>
</video_subhead>



<style>
#background_video {
  width: 100vw;
  height: 100vh;
  object-fit: cover;
  position: fixed;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  z-index: -1;
}

video_head, video_subhead {

  color: ;
  opacity: 0.0;
  font-family: Arial;
  font-weight: bold;
  text-align: center;
}

video_head {
  font-size: 6rem;
  margin-top: 30vh;
}

video_subhead { font-size: 3rem; }

  @media (max-width: 750px) {
    #background_video { display: none; }
    body {
      background: url("") repeat;
      background-size: 100vh cover;
    }
}
  
</style>

Here is some text in curly braces: {{ my.first.article }}