style.css

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

body {
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  background-color: white;
}

.main-container {
  background-color: black;
  border-radius: 30px;
  padding: 30px;
}

header {
  height: 70px;
  display: flex;
  align-items: center;
  justify-content: space-around;
  color: grey;
}

.volume {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  width: 120px;
  height: 50px;
  font-size: 24px;

}
.volume >input {
  accent-color: #fff;
}
.show-key {
  display: flex;
  align-items: center;
  justify-content: space-around;
  font-size: 25px;
  width: 140px;
}

[type],
.key {
  cursor: pointer;
}

.toggle {
  appearance: none;
}

.toggle-label {
  border: 1px solid gray;
  border-radius: 100px;
  width: 80px;
  height: 40px;
  padding: 3px;
  outline: none;
  position: relative;
}

.circle {
  width: 30px;
  height: 100%;
  border-radius: 50%;
  background-color: ghostwhite;
  transition: transform 200ms linear;
}

.toggle:checked+.toggle-label {
  background-color: gray;
}

.piano-box {
  display: flex;
  margin-top: 40px;

}

.key {
  list-style: none;
  text-transform: uppercase;
  position: relative;
  font-size: 24px;
}

.white {
  width: 60px;
  height: 200px;
  background-color: #fff;
  border-radius: 10px;
  border: 1px solid black;
}

.white.active {
  box-shadow: 0 0 0 1px #000000 inset,
    0 0 0 1px rgba(0, 0, 0, 0.4);
}

.black {
  width: 40px;
  height: 120px;
  background-color: #000000;
  border-radius: 0 0 7px 7px;
  margin: 0 -20px;
  z-index: 2;
  color: gray;
}

.black.active {
  box-shadow: 0 0 2px 1px #ffffff inset,
    0 0 2px rgba(217, 213, 213, 0.15) inset,
    0 0 0 -2px rgba(255, 255, 255, 0.4);
}

.key>span {
  position: absolute;
  bottom: 20px;
  width: 100%;
  text-align: center;
}

.hidden {
  display: none;
}