YouTube Full Theater

@-moz-document url-prefix("https://www.youtube.com/watch") {

ytd-watch-flexy[theater] #player-full-bleed-container.ytd-watch-flexy,
ytd-watch-flexy[theater] #full-bleed-container.ytd-watch-flexy {
  height: 100vh;
  max-height: none;
}
.ytp-iv-video-content {
    height: 100vh!important;
    width:100vw!important;
    left:0!important;
    top:0!important;
}
#page-manager.ytd-app {
  margin-top: 0;
}
#masthead-container {
  opacity: 0;
  transition:0.5s;
}
#content:hover #masthead-container {
  opacity: 0.75;
  animation: stylus-fadeout 0.5s 3s forwards;
}
@keyframes stylus-fadeout {
  from {opacity: 0.75;}
  to {opacity: 0;}
}
#content:hover #masthead-container:focus-within,
#masthead-container:focus-within {
  opacity: 1!important;
}
#masthead {
  --yt-swatch-primary: rgba(0,0,0,0.5)!important;
  transition: 0.25s;
}
#content:hover #masthead-container:focus-within #masthead,
#masthead-container:focus-within #masthead {
  --yt-swatch-primary: rgb(35,35,35)!important;
}
}