* { margin: 0; padding: 0; box-sizing: border-box; }

html, body {
  background: #000;
  width: 100%;
  height: 100vh;
  height: 100dvh;
  overflow: hidden;
}

#game-container {
  width: 100%;
  height: 100%;
}

#back-btn {
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 100;
  font-family: 'Press Start 2P', monospace;
  font-size: 8px;
  color: #444;
  text-decoration: none;
  padding: 7px 12px;
  border: 1px solid #2a2a2a;
  background: rgba(0, 0, 0, 0.85);
  transition: color 0.15s, border-color 0.15s;
}

#back-btn:hover {
  color: #00ff00;
  border-color: #00ff00;
}