.piano-container {
  max-width: 1200px;
  margin: 40px auto;
  padding: 20px;
  background: #f5f5f5;
  border-radius: 15px;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
}

.controls {
  margin-bottom: 30px;
  display: flex;
  justify-content: center;
  gap: 15px;
  flex-wrap: wrap;
}

.btn {
  border: none;
  color: white;
  cursor: pointer;
  border-radius: 8px;
  font-weight: 500;
  transition: all 0.3s ease;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  font-size: 1rem !important;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.btn-notes {
  background: linear-gradient(145deg, #4caf50, #45a049);
}
.btn-mark {
  background: linear-gradient(145deg, #2196f3, #1e88e5);
}
.btn-play {
  background: linear-gradient(145deg, #ff9800, #f57c00);
}
.btn-clear {
  background: linear-gradient(145deg, #f44336, #e53935);
}

.piano {
  display: flex;
  position: relative;
  height: 320px;
  background: linear-gradient(to bottom, #fff 0%, #f9f9f9 100%);
  border-radius: 0 0 8px 8px;
  border: 2px solid #333;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
  padding: 0 10px;
  overflow-x: auto;
}

.white-key {
  flex: 1;
  height: 100%;
  background: linear-gradient(to bottom, #fff 0%, #f9f9f9 100%);
  border-left: 1px solid #ccc;
  border-bottom: 8px solid #ccc;
  position: relative;
  z-index: 1;
  transition: all 0.1s ease;
  border-radius: 0 0 4px 4px;
  min-width: 50px;
}

.white-key:last-child {
  border-right: 1px solid #ccc;
}

.black-key {
  width: 32px;
  height: 60%;
  background: linear-gradient(to bottom, #333 0%, #000 100%);
  position: absolute;
  z-index: 2;
  border-radius: 0 0 4px 4px;
  transition: all 0.1s ease;
  top: 0;
  transform: translateX(-50%);
}

.white-key.active {
  background: linear-gradient(to bottom, #e3f2fd, #bbdefb);
  transform: translateY(2px);
}

.black-key.active {
  background: linear-gradient(to bottom, #555, #333);
  transform: translateY(2px) translateX(-50%);
}

.white-key.marked {
  background: linear-gradient(to bottom, #fff0e1, #ffe0b2);
}

.black-key.marked {
  background: linear-gradient(to bottom, #4a4a4a, #333);
}

.white-key .note-label,
.black-key .note-label {
  display: none;
  position: absolute;
  bottom: 15px;
  left: 50%;
  transform: translateX(-50%);
  color: #333;
  font-size: 14px;
  font-weight: 500;
}

.black-key .note-label {
  color: white;
  bottom: 20px;
}

.white-key.show-notes .note-label,
.black-key.show-notes .note-label {
  display: block;
}

.piano {
  user-select: none;
  -webkit-user-select: none;
}