video_player/src/DefaultPlayer/Captions/Captions.css

.component {
    position: relative;
}

.component:hover {
    background-color: #000;
}

.button {
    width: 34px;
    height: 34px;
    background: none;
    border: 0;
    color: inherit;
    font: inherit;
    line-height: normal;
    overflow: visible;
    padding: 0;
    cursor: pointer;
}

.button:focus {
    outline: 0;
}

.icon {
    padding: 5px;
}

.trackList {
    position: absolute;
    right: 0;
    bottom: 100%;
    display: none;
    background-color: rgba(0,0,0,0.7);
    list-style: none;
    padding: 0;
    margin: 0;
    color: #fff;
}

.component:hover .trackList {
    display: block;
}

.trackItem {
    padding: 7px;
    cursor: pointer;
}

.activeTrackItem,
.trackItem:hover {
    background: #000;
}

.activeTrackItem {
    composes: trackItem;
    text-decoration: underline;
}