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

html, body {
  width: 100%;
  height: 100%;
  height: 100dvh;
  overflow: hidden;
  overscroll-behavior: none;
  background: #0f0a2a;
  display: flex;
  align-items: center;
  justify-content: center;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

canvas {
  display: block;
  max-width: 100%;
  max-height: 100%;
  image-rendering: pixelated;
}

#backBtn {
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 100;
  padding: 6px 14px;
  background: rgba(30, 20, 60, 0.75);
  color: #e0d0ff;
  font: bold 14px "Segoe UI", system-ui, sans-serif;
  text-decoration: none;
  border: 2px solid rgba(180, 140, 255, 0.5);
  border-radius: 20px;
  backdrop-filter: blur(6px);
  transition: background 0.2s, border-color 0.2s;
}

#backBtn:hover {
  background: rgba(60, 40, 110, 0.85);
  border-color: rgba(200, 170, 255, 0.8);
}