* { margin: 0; padding: 0; box-sizing: border-box; }
html, body {
  width: 100%; height: 100%;
  background: #1A1F3A;
  overflow: hidden;
  touch-action: none;
  -webkit-user-select: none;
  user-select: none;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", sans-serif;
}
#game-container {
  width: 100vw; height: 100vh;
  display: flex; align-items: center; justify-content: center;
}
canvas { display: block; }