body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: #f4f4f4;
  margin: 0;
  padding: 20px;
  box-sizing: border-box;
  display: flex;
  justify-content: center;
  min-height: 100vh;
}

.container {
  display: flex;
  width: 100%;
  max-width: 1200px;
  background: white;
  border-radius: 15px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
  overflow: hidden;
}

.controls {
  flex: 1;
  padding: 30px;
  background: #fafafa;
  transition: background-color 0.3s;
}

.controls.playing {
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0% {
    background-color: #fafafa;
  }

  50% {
    background-color: #e6f3e6;
  }

  100% {
    background-color: #fafafa;
  }
}

.instructions {
  flex: 2;
  padding: 30px;
  overflow-y: auto;
}

h2 {
  color: #333;
  margin-bottom: 20px;
}

.control-group {
  margin-bottom: 15px;
}

label {
  display: block;
  margin-bottom: 5px;
  color: #555;
}

input[type="number"],
select {
  width: 100%;
  padding: 8px;
  border: 1px solid #ddd;
  border-radius: 5px;
  box-sizing: border-box;
}

.note-select {
  display: flex;
  gap: 10px;
}

.note-select select {
  flex: 1;
}

.volume-control {
  display: flex;
  align-items: center;
}

.volume-control input[type="range"] {
  flex: 1;
  margin: 0 10px;
}

.volume-control span {
  min-width: 30px;
  text-align: right;
  color: #333;
}

.volume-buttons {
  display: flex;
  gap: 5px;
}

.volume-buttons button {
  background: #eee;
  border: 1px solid #ddd;
  padding: 5px 10px;
  cursor: pointer;
  border-radius: 5px;
}

.volume-buttons button:hover {
  background: #ddd;
}

button#playButton {
  width: 100%;
  border: none;
  padding: 12px;
  cursor: pointer;
  border-radius: 5px;
  font-size: 16px;
  margin-top: 10px;
  transition: background-color 0.3s, color 0.3s;
}

button#playButton.play {
  background-color: #4CAF50;
  color: white;
}

button#playButton.stop {
  background-color: #f44336;
  color: white;
}

button#playButton.hold-active {
  background-color: #2196F3;
  color: white;
}

button#playButton.play:hover {
  background-color: #45a049;
}

button#playButton.stop:hover {
  background-color: #d32f2f;
}

button#playButton.hold-active:hover {
  background-color: #1976D2;
}

#status {
  text-align: center;
  margin-top: 15px;
  font-weight: bold;
  color: #333;
}

#status.playing {
  color: #4CAF50;
  animation: blink 1s infinite;
}

.play-instruction {
  font-size: 0.85em;
  color: #666;
}

@keyframes blink {
  50% {
    opacity: 0.5;
  }
}

.instructions h3 {
  color: #333;
  margin-bottom: 10px;
}

.instructions p,
.instructions ol,
.instructions ul {
  color: #555;
  line-height: 1.6;
}

.instructions ol,
.instructions ul {
  padding-left: 20px;
}

.instructions li {
  margin-bottom: 10px;
}

.footer {
  text-align: center;
  margin-top: 20px;
  color: #777;
}

.footer a {
  color: #4CAF50;
  text-decoration: none;
}

.footer a:hover {
  text-decoration: underline;
}

@media (max-width: 900px) {
  .container {
    flex-direction: column;
  }

  .controls,
  .instructions {
    flex: none;
    max-height: none;
  }
}