body{display:flex;justify-content:center;align-items:center;min-width:100vw;min-height:100vh;margin:0}.piano{display:flex}.key{background-color:#fff;height:300px;width:60px;border:2px solid black}.key.flat{position:relative;background-color:#000;margin-left:-17px;margin-right:-17px;height:200px;width:30px;z-index:2}.key:hover{cursor:pointer;background-color:#b8b812}.key.flat.selectedKey,.selectedKey{background-color:gray}