* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html, body {
  height: 100%;
  overflow: hidden;
  background: black;
}

video {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

/* Show only desktop video by default */
#desktopVideo {
  display: block;
}
#mobileVideo {
  display: none;
}

/* Switch to mobile under 768px */
@media (max-width: 768px) {
  #desktopVideo {
    display: none;
  }
  #mobileVideo {
    display: block;
  }
}