html, body {
  margin: 0;
  padding: 0;
  background: #0b0b12;
  height: 100%;
  overflow: hidden;
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
}
body {
  display: flex;
  align-items: center;
  justify-content: center;
}
/* 画布:宽度逻辑 180 固定,高度由 JS 按屏幕比例设定(300~480),并由 JS 等比缩放居中(letterbox) */
#game {
  image-rendering: pixelated;
  image-rendering: crisp-edges;
  touch-action: none;
  background: #0b0b12;
  max-width: 100vw;
  max-height: 100dvh;
}