main.css

/* * { */
/*   border: 1px solid gray; */
/* } */

html, body {
  padding: 0;
  margin: 0;
}

body {
  display: flex;
  flex-direction: column;
  justify-content: center;

  font-family: "Museo Sans Rounded", sans-serif;

  color: white;
  background-color: #1cb0f6;
}

.page-header {
  display: flex;
  justify-content: center;

  font-size: 2rem;
}

.subtitle {
  /* display: flex; */
  /* justify-content: center; */
  color: #4c4c4c;
  font-size: 1.3em;
  text-align: center;
  padding: 0;
  margin: 0;

}

.keys {
  display: flex;
  justify-content: center;
  align-items: center;

  height: 400px;
}

.key {
  display: flex;
  justify-content: center;
  align-items: flex-end;

  width: 60px;
  height: 204px;
  padding-bottom: 5px;

  text-align: center;
  transition: all .07s ease;

  color: black;
  background-color: white;
}

kbd {
  display: flex;
  justify-content: center;

  font-family: "Museo Sans Rounded", sans-serif;
  font-size: 4rem;
}

.sound {
  color: #afafaf;
}

.key__black {
  width: 40px;
  height: 104px;
  background-color: black;
}

.border-right {
  border-right: 1px solid black;
}

.playing {
  transform:scale(1.1);
}

@media only screen and (max-width: 768px) {
  div.key__black {
    display: none;
  }

  div.key {
    border-right: 1px solid black;
  }
}