body {
  margin: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: linear-gradient(to bottom right, #4facfe, #00f2fe);
}

.game-container {
  text-align: center;
  background-color: rgba(255,255,255,0.95);
  padding: 30px 50px;
  border-radius: 20px;
  box-shadow: 0 10px 25px rgba(0,0,0,0.3);
  width: 320px;
}

h1 {
  margin-bottom: 10px;
  font-size: 1.8rem;
  color: #333;
}

.level-display {
  font-weight: bold;
  margin-bottom: 20px;
}

.color-buttons {
  display: grid;
  grid-template-columns: repeat(2, 120px);
  grid-template-rows: repeat(2, 120px);
  gap: 15px;
  justify-content: center;
  margin-bottom: 20px;
}

.color-btn {
  border: none;
  border-radius: 20px;
  cursor: pointer;
  transition: transform 0.2s, opacity 0.2s;
  opacity: 0.9;
}

.color-btn:active,
.color-btn.active {
  transform: scale(1.1);
  opacity: 1;
  box-shadow: 0 5px 15px rgba(0,0,0,0.3);
}

#green { background-color: #28a745; }
#red { background-color: #dc3545; }
#yellow { background-color: #ffc107; }
#blue { background-color: #007bff; }

.controls button {
  padding: 10px 20px;
  margin: 5px;
  border: none;
  border-radius: 10px;
  font-weight: bold;
  cursor: pointer;
  transition: background 0.3s;
}

#start-btn { background-color: #28a745; color: #fff; }
#restart-btn { background-color: #dc3545; color: #fff; }

.controls button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

#message {
  margin-top: 15px;
  font-weight: bold;
  color: #333;
  min-height: 1.2em;
}