.player {
    width: 21px;
    height: 21px;
    background: none;
    border: 1px solid transparent;
}

.player:active {
    outline: 0;
}

.player > .play {
    width: 0px;
    height: 0px;
    border-top: 8px solid transparent;
    border-bottom: 8px solid transparent;
    border-left: 10px solid green;
}

.player > .stop {
    background-color: red;
    width: 15px;
    height: 15px;
}