style.css

body {
  font-family: Verdana, Geneva, Tahoma, sans-serif;
}

#welcome {
  padding: 0px 50px;
}

#play-button {
  font-size: 24px;
  background-color: mediumslateblue;
  color: white;
  border: none;
  cursor: pointer;
  padding: 5px 15px;
  border-radius: 10px;
  transition: .3s;
} #play-button:hover {
  transform: scale(1.1);
  background-color: slateblue;
}

#main {
  display: none;
}

.upper > .left {
  float: left;
}

.lower {
  clear: left;
  padding: 10px;
  height: 50px;
  margin-bottom: 10px;
}

.menu {
  margin: 10px;
  border-top: 3px solid #ccc;
}

.white-key {
  width: 8px;
  height: 50px;
  border: 1px solid black;
  float: left;
  transform: scaleX(2.6);
  z-index: 0;
  position: relative;
}

.black-key {
  width: 13px;
  height: 30px;
  background-color: black;
  float: left;
  z-index: 1;
  position: relative;
}

.radio-span {
  white-space: nowrap;
}