styles.css

body {
  background-color: lightseagreen;
}

.black-keys {
  display: flex;
  height: 97vh;
  width: 99vw;
  justify-content: center;
  align-items: center;
}

.black-keys kbd {
  bottom: 25px;
  display: inline-block;
  height: 150px;
  width: 50px;
  font-size: 35px;
  color: #fff;
  text-align: center;
  border-width: 2px;
  border-style: solid;
  border-color: #000;
  border-radius: 12px;
  background-color: #000;
}

.left-keys {
  position: relative;
  left: 23px;
  margin-left: -50px;
  margin-right: 68px;
}

.right-keys {
  position: relative;
  left: 44px;
  margin-right: 15px;
}

.white-keys {
  position: absolute;
  display: flex;
  height: 97vh;
  width: 99vw;
  justify-content: center;
  align-items: center;
}

.white-keys kbd {
  display: inline-block;
  height: 200px;
  width: 70px;
  border-style: solid;
  border-width: 2px;
  border-radius: 12px;
  font-size: 35px;
  text-align: center;
  line-height: 10;
  background-color: #fff;
}