jellyfin-web/dashboard-ui/css/chromecast.css

.btnCast {
    width: 28px;
    height: 28px;
    padding: 0;
    background-color: transparent;
    border: 0;
    background-size: 100%;
    vertical-align: middle;
    margin: 0 .6em;
    cursor: pointer;
    border: 0 !important;
}

    .btnCast:hover {
        opacity: .5;
    }

.btnDefaultCast {
    background-image: url(images/chromecast/ic_media_route_off_holo_dark.png);
}

.btnActiveCast {
    background-image: url(images/chromecast/ic_media_route_on_holo_dark.png);
}

.btnDisabledCast {
    background-image: url(images/chromecast/ic_media_route_disabled_holo_dark.png);
}

.ui-icon-ccast {
    background-image: url(images/chromecast/ic_media_route_off_holo_dark.png);
    background-position: 5px 5px;
    background-repeat: no-repeat;
	background-size: 18px 18px;
}