main.css

/* GENERAL */
html {
  background: url(background.jpg);
  background-size: cover;
  background-repeat: no-repeat;
  font-family: 'Bahiana', cursive;

}
h1 {
  font-size: 8em;
  text-align: center;
  text-transform: uppercase;
}
/* NOTES */
kbd {
  display: block;
  font-size: 3rem;
}
.keys {
  display: flex;
  flex: 1;
  min-height: 100vh;
  align-items: center;
  justify-content: center;
}

.key {
  border: .2rem solid black;
  border-radius: 5rem;
  margin: 1rem;
  font-size: 1.5rem;
  padding: 1rem .5rem;
  transition: all .07s ease;
  width: 10rem;
  text-align: center;
  color: white;
  background: rgba(0,0,0,0.4);
  text-shadow: 0 0 .5rem black;
}
/* ACTION */
.playing {
  transform: scale(1.1);
  border-color: white;
  box-shadow: 0 0 1rem black;
}
.sound {
  font-size: 2rem;
  text-transform: uppercase;
  color: white;
}