style.css

* {
  margin: 0;
  padding: 0;
}

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

body {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-repeat: no-repeat;
  background-size: cover;
  background-position: center;
  background: url('images/drum.jpg');
  font-family: 'Mochiy Pop P One', Arial, Helvetica, sans-serif;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
}

.key {
  width: 95px;
  height: 100px;
  background-color: rgba(0, 0, 0, 0.438);
  border: 4px solid #000;
  border-radius: 6px;
  transition: all 0.07s;
}

.legend {
  text-align: center;
  color: #ffc600;
  letter-spacing: 1px;
  font-family: Arial, Helvetica, sans-serif;
  text-transform: uppercase;
}

.list {
  list-style: none;
  display: flex;
  justify-content: space-between;
  width: 100%;
  margin-top: 20%;
}

.symbol {
  color: #fff;
  font-size: 35px;
  text-align: center;
  margin-top: 6px;
  margin-bottom: 10px;
}

.playing {
  transform: scale(1.1);
  border-color: #ffc600;
  box-shadow: 0 0 10px #ffc600;
}