html, body {
  margin: 0;
  padding: 0;
  background: #181820;
  color: #ddd;
  font-family: "Segoe UI", "Microsoft YaHei", sans-serif;
  height: 100%;
}
#wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  gap: 10px;
}
#game {
  width: min(96vw, 768px);
  aspect-ratio: 16 / 15;
  image-rendering: pixelated;
  image-rendering: crisp-edges;
  background: #000;
  box-shadow: 0 0 0 4px #000, 0 0 40px rgba(0,0,0,.8);
}
#help {
  font-size: 13px;
  line-height: 1.7;
  color: #aab;
  text-align: center;
  max-width: 760px;
  padding: 0 10px 16px;
}
#help b { color: #fff; }