body {
  font-family: "Arial", sans-serif;
  background-color: #f2f8ff;
  margin: 0;
  padding: 0;
}

.app {
  max-width: 480px;
  margin: 0 auto;
  padding: 20px;
  text-align: center;
}

h1 {
  color: #6a5acd;
  margin-bottom: 20px;
}

.note-image img {
  width: 100%;
  max-width: 300px;
  height: auto;
  margin-bottom: 20px;
}

.question {
  margin-bottom: 20px;
}

.clef-buttons,
.note-buttons {
  display: grid;
  flex-wrap: wrap;
  justify-content: center;
  grid-template-columns: repeat(2, 1fr);
  max-width: 300px;
  gap: 10px;
  margin: 0 auto;
}

button {
  padding: 10px 16px;
  border: none;
  border-radius: 8px;
  background-color: #add8e6;
  color: #333;
  font-size: 16px;
  cursor: pointer;
  transition: background-color 0.2s;
}

button:hover {
  background-color: #87cefa;
}

button:active {
  background-color: #6ab7f5;
}
button.selected {
  background-color: #a0d8ef; /* 水色で選択中を表現 */
  color: white;
}

.controls {
  margin-top: 20px;
  display: flex;
  justify-content: center;
  gap: 15px;
  flex-wrap: wrap;
}

.result {
  margin-top: 10px;
  font-size: 18px;
  color: #8a2be2;
  font-weight: bold;
}