Full Theatre - YouTube by TGekko

/* ==UserStyle==
@name        Full Theatre - YouTube
@namespace   youtube.com
@version     1.0.0
@license     MIT
@author      TGekko (https://www.tgekko.com/)
@description Remove distractions while distracting yourself! Make YouTube's theatre mode fill the window instead of becoming only slightly larger.
==/Userstyle== */

@-moz-document domain('youtube.com') {
 html:has([theater]:not([fullscreen])) {
  overflow-x: hidden;
  scrollbar-color: auto;
  ::-webkit-scrollbar {
   width: 0.5em;
   height: 0.5em;
   &:hover {
    width: 1em;
    height: 1em;
   }
  }
  ::-webkit-scrollbar-track {
   background-color: black;
  }
  ::-webkit-scrollbar-thumb {
   background-color: black;
   border-radius: 0.5em;
   &:hover {
    background-color: #FFF5;
   }
  }
  ::-webkit-scrollbar-corner {
   background-color: black;
  }
 }
 ytd-masthead[theater]:not([fullscreen]) {
  position: sticky;
 }
 ytd-watch-flexy[theater]:not([fullscreen]),
 [theater]:not([fullscreen]) .html5-video-player {
  position: absolute;
  top: 0px;
  background: black;
  width: 100vw;
  height: 100vh;
 }
 [theater]:not([fullscreen]) .html5-video-player  {
  z-index: 10000;
 }
 [theater]:not([fullscreen]) #columns {
  position: absolute;
  top: 100vh;
 }
}