youtube-full.user.css

/* ==UserStyle==
@name         youtube.com full-height theater
@version      20230830.07.59
@namespace    nathyong.github.io
@description  little tweak that makes player in theater mode take almost entire height of the screen (still with topbar visible)


@author       nathyong
@license      No License
==/UserStyle== */

@-moz-document domain("youtube.com") {
ytd-watch-flexy[theater]:not([fullscreen]) #full-bleed-container.ytd-watch-flexy,
ytd-watch-flexy[theater]:not([fullscreen]) #player-full-bleed-container.ytd-watch-flexy {
	height: 100vh;
	max-height: 100vh;
}

ytd-app:not([guide-persistent-and-visible]) ytd-page-manager {
  margin-top: 0!important;
}

ytd-app:not([guide-persistent-and-visible]) #player-theater-container:empty~#columns #primary,
ytd-app:not([guide-persistent-and-visible]) #player-theater-container:empty~#columns #secondary{
    padding-top: 56px;
}

ytd-app:not([guide-persistent-and-visible]) ytd-masthead,
ytd-app:not([guide-persistent-and-visible]) #masthead-container.ytd-app::after {
  transform: translateY(-56px);
  transition: transform .1s .5s ease-out;
}
ytd-app:not([guide-persistent-and-visible]) #masthead-container:hover ytd-masthead,
ytd-app:not([guide-persistent-and-visible]) #masthead-container:hover.ytd-app::after {
  transform: translateY(0px);
}    
}