html,
body {
  width: 200px;
}

body {
  margin: 0;
}

.button {
  margin: 0;
  padding: 4px 20px;
  text-align: center;
  font-size: 1.5em;
  cursor: pointer;
}

.button:hover {
  background: #97c4ff;
}

.selected {
  background: #4294ff;
}

.selected:hover {
  background: #4294ff;
}