#app{position:relative;height:28vw;margin:6vw}#app .key{position:absolute;border:solid 2px gray;border-radius:1vw;background-color:#fff;color:#000;transition-duration:.25s;transition-timing-function:ease-in-out;transition-property:color,background-color}#app .key.active{background-color:#000;color:#fff}