jellyfin-web/dashboard-ui/themes/holiday/style.css

.background-theme-b .backgroundContainer.withBackdrop {
    background: rgba(6, 6, 6, .86) !important;
}

.ui-body-b h1, .ui-body-b h2 {
    color: #E53A35;
}

.holidayInfoButton {
    color: #E53A35 !important;
}

.libraryViewNav .ui-btn-active {
    border-bottom-color: #AC3326 !important;
    color: #AC3326 !important;
}

.channelTimeslotHeader, .timeslotHeader {
    background: #cc3333 !important;
}

.channelTimeslotHeader {
    border-right-color: #cc3333 !important;
}

.playedIndicator {
    background-color: #cc3333 !important;
}

.darkDrawer .sidebarLink:hover {
    background: #AC3326;
}

.darkDrawer .sidebarLink.selectedSidebarLink, .darkDrawer .selectedMediaFolder {
    background: #AC3326 !important;
}

#snowflakeContainer {
    position: absolute;
    left: 0px;
    top: 0px;
    pointer-events: none;
}

.snowflake {
    padding-left: 15px;
    font-family: Cambria, Georgia, serif;
    font-size: 14px;
    line-height: 24px;
    position: fixed;
    color: #FFFFFF;
    user-select: none;
    z-index: 1000;
}

    .snowflake:hover {
        cursor: default;
    }

.christmas .mainDrawer {
    background-image: url(https://raw.githubusercontent.com/MediaBrowser/Emby.Resources/master/themes/holiday/drawer.jpg);
    background-size: cover;
    background-position: 60% center;
    background-repeat: no-repeat;
}