body {
  font-family: sans-serif;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  min-height: 100vh;
  background: url(cat-in-space.gif) no-repeat bottom;
  background-size: cover;
}

ul {
      list-style: none;
    display: flex;
    width: 100vw;
    max-width: 900px;
    height: 20vh;
    justify-content: center;
    flex-flow: row wrap;
    padding: 0;
}

ul .key {
    position: relative;
    width: 14%;
    height: 100%;
    border: 1px solid black;
    border-right: none;
    background: #fffff0;
    border-radius: 5px;
    box-shadow: 0px 3px 5px #666;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: flex-end;
    padding-bottom: 10px;
    font-weight: bold;
}
}

ul .key:last-child {
  border-right: 1px solid black;
}

ul .black-key {
 position: absolute;
    top: -1px;
    left: 75%;
    width: 50%;
    height: 70%;
    background: black;
    border-radius: 5px;
    box-shadow: 0px 3px 5px #666;
    z-index: 10;
    display: flex;
    justify-content: center;
    align-items: flex-end;
    padding-bottom: 10px;
    color: white;
}

ul .active {
  box-shadow: 0px 1px 3px #666;
}