Arc Boost - youtube all black full windowed theatre player

styles.css

body, ytd-app, ytd-masthead {
  --yt-spec-brand-background-solid: black !important;
  --ytd-searchbox-background: black !important;
  --yt-spec-base-background: black !important;
  --yt-spec-raised-background: black !important;
  --yt-spec-general-background-a: black !important;
  --yt-spec-general-background-b: black !important;
  --yt-spec-general-background-c: black !important;
  --yt-spec-brand-background-primary: black !important;
  background: black !important;
}

.html5-video-container {
  height: 100%;
  width: 100%;
  top: 0px;
  left: 0px;
}

#player-theater-container:not(:empty) {
  max-height: none !important;
  width: 100% !important;
  height: calc(100vh - 64px) !important;
}