My youtube css

/*Audio only*/
video { display: none !important;}
/*Player height*/
#player .player-api, #placeholder-player .player-api { height: 40px;}
/*Background*/
.ytp-iv-video-content{  background: url("https://s3.envato.com/files/231857282/Preview%20Mexico%20590x332.jpg");}
#player-playlist .watch-playlist{   background: url("https://st2.depositphotos.com/1859105/6997/i/950/depositphotos_69979599-stock-photo-wood-table-top-background-and.jpg");}
#player-playlist .playlist-videos-list,
#player-playlist .playlist-videos-list li, #player-playlist .playlist-videos-list .yt-ui-ellipsis
{   background: transparent;}

.hidden{display: none;}

<script>
// Remove related videos
$(document).ready(function () {
    setInterval(function() {
    if ($('#watch-appbar-playlist').length)
        $('#watch7-sidebar').addClass('hidden');
    else
        $('#watch7-sidebar').css('margin-top', '5%');
    }, 60000);
});

// Media play key
$(document).keyup(function(e) {
  if (e.keyCode==179)
    $('.ytp-play-button').trigger('click');
});

</script>