*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  background-color: #143f6b;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

.piano {
  display: flex;
}

.key {
  width: var(--width);
  height: calc(var(--width) * 4);
}

.white {
  --width: 100px;
  background-color: #fff;
  border: 1px solid #333;
}
.white.active {
  background-color: #ccc;
}

.black {
  --width: 60px;
  background-color: #000;
  margin-left: calc(var(--width) / -2);
  margin-right: calc(var(--width) / -2);
  z-index: 2;
}

.black.active {
  background-color: #333;
}