/* --- Style général --- */
body {
  margin: 0;
  padding: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: radial-gradient(circle at center, #e0f7fa, #81d4fa);
  color: #333;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

/* --- Écran d’accueil --- */
#start-screen {
  text-align: center;
  background-color: rgba(255, 255, 255, 0.9);
  padding: 40px;
  border-radius: 20px;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.2);
}

#start-screen h1 {
  font-size: 3rem;
  margin-bottom: 20px;
  color: #0277bd;
}

#start-screen button {
  font-size: 18px;
  padding: 12px 24px;
  margin: 10px;
  border: none;
  border-radius: 12px;
  background: linear-gradient(to right, #4caf50, #81c784);
  color: white;
  cursor: pointer;
  transition: all 0.3s ease-in-out;
}

#start-screen button:hover {
  transform: scale(1.05);
  background: linear-gradient(to right, #388e3c, #66bb6a);
}

/* --- Canvas jeu --- */
canvas {
  border: 3px solid #1a237e;
  border-radius: 12px;
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.3);
}

/* --- Mode sombre --- */
.dark-mode {
  background: radial-gradient(circle at center, #121212, #1e1e1e);
  color: #f0f0f0;
}

.dark-mode #start-screen {
  background-color: rgba(30, 30, 30, 0.9);
}

.dark-mode button {
  background: linear-gradient(to right, #757575, #9e9e9e);
}

.dark-mode button:hover {
  background: linear-gradient(to right, #616161, #bdbdbd);
}

.dark-mode canvas {
  filter: brightness(0.85);
  border-color: #90caf9;
}