youtube 1920 > 1280

usercss.css

body {
    font-family: tahoma, arial;
}

.ytp-hide-info-bar:hover .ytp-chrome-top {
    display: inherit !important;
}

.ytp-hide-info-bar .ytp-chrome-top > .ytp-title {
    display: none !important;
}

.ytp-hide-info-bar .ytp-chrome-top-buttons > .ytp-share-button {
    display: none !important;
}

body, input, button, textarea, select {
    font-family: tahoma, arial;
}

.iv-branding .branding-img-container {
    display: none !important;
}

.player-width {
    width: 854px !important;
}

.player-height {
    height: 480px !important;
}

.iv-btp-companion {
    height: 152px;
}

.iv-btp-card {
    height: 120px;
    width: 250px;
    margin-left: 10px;
    padding-left: 10px;
}

.iv-btp-card-short-info {
    display: none;
}

.iv-btp-card-long-info {
    display: inline;
}

.ad-carousel-clip {
    margin-right: 30px;
}

.ad-carousel-nav-button {
    top: 90px;
}

#player-messages .mealbar-promo-renderer .yt-dialog-base {
    top: 485px;
    width: 854px;
}

#watch7-content {
    width: 854px;
}

#page.watch .content-alignment {
    max-width: 1280px;
}

#watch7-preview {
    margin-top: -480px;
}

#player-playlist .watch-playlist {
    left: 864px;
}

#watch7-sidebar {
    margin-left: 864px;
    top: -120px;
}

#watch7-sidebar-contents {
    min-height: 640px;
}

.html5-video-player .video-stream {
    width: 854px !important;
    height: 480px  !important;
    left: 0  !important;
    top: 0  !important;
}

.ytp-chrome-bottom {
    width: 835px !important;
}