:root {
  color-scheme: dark;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  width: 100%;
  height: 100%;
  background: #04050a;
  overflow: hidden;
  font-family: "Segoe UI", "Malgun Gothic", sans-serif;
}

#stage {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
}

#game {
  display: block;
  background: #04050a;
  cursor: crosshair;
  touch-action: none;
}

.back-btn {
  position: fixed;
  top: calc(10px + env(safe-area-inset-top));
  left: calc(10px + env(safe-area-inset-left));
  z-index: 10;
  color: #5ad9ff;
  text-decoration: none;
  font-weight: 700;
  font-size: 0.85rem;
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 5px 10px;
  border-radius: 8px;
  background: rgba(90, 217, 255, 0.12);
  border: 1px solid rgba(90, 217, 255, 0.25);
  transition: all 0.2s;
}

.back-btn:hover {
  background: rgba(90, 217, 255, 0.25);
  transform: translateX(-2px);
}