For whatever reason, youtube fixes the frame to 16:9 in theater mode, but this should fix it removing top and bottom black bar
/* ==UserStyle==
@name Youtube Theater mode 21:9 widescreen (and others) fix
@version 1.0.0
@description For whatever reason, youtube fixes the frame to 16:9 in theater mode, but this should fix it removing top and bottom black bar
@author toppits
@namespace https://greasyfork.org/users/371090
==/UserStyle== */
@-moz-document domain("youtube.com"){
video.video-stream.html5-main-video {
top: 0 !important;
}
ytd-watch-flexy[theater] #player-theater-container.ytd-watch-flexy {
height: calc(var(--ytd-watch-flexy-height-ratio) / var(--ytd-watch-flexy-width-ratio) * (100vw - 12px)) !important;
max-height: calc(100vh - 150px) !important;
}
ytd-watch-flexy[fullscreen] #player-theater-container.ytd-watch-flexy {
height: 100vh !important;
max-height: 100vh !important;
}
}