body {
  margin: 0;
  background-color: #101820;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  flex-direction: column;
  color: #00bfff;
  font-family: "Poppins", sans-serif;
}

#startScreen {
  text-align: center;
}

#startButton {
  background-color: #00bfff;
  border: none;
  color: white;
  font-size: 1.2rem;
  padding: 10px 25px;
  border-radius: 10px;
  cursor: pointer;
  transition: background 0.3s;
}

#startButton:hover {
  background-color: #0096cc;
}

canvas {
  display: none;
  border: 3px solid #00bfff;
  border-radius: 12px;
  background-color: #0f2233;
}

.back-btn {
  display: inline-block;
  margin: 20px;
  padding: 10px 20px;
  color: #e0f7ff;
  background: rgba(0, 170, 255, 0.2);
  border: 1px solid rgba(0, 170, 255, 0.4);
  border-radius: 10px;
  text-decoration: none;
  font-weight: 600;
  letter-spacing: 1px;
  box-shadow: 0 0 10px rgba(0,170,255,0.5);
  backdrop-filter: blur(6px);
  transition: all 0.3s ease;
  position: fixed;
  top: 20px;
  left: 20px;
  z-index: 999;
}

.back-btn:hover {
  background: rgba(0, 170, 255, 0.4);
  box-shadow: 0 0 25px rgba(0,170,255,0.8);
  transform: scale(1.05);
}