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

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: #000;
  touch-action: none;
  overscroll-behavior: none;
  -webkit-user-select: none;
  user-select: none;
  font-family: 'Courier New', monospace;
}

#game-container {
  position: relative;
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
}

#game {
  background: #111;
  display: block;
  touch-action: none;
}

#mute-btn {
  position: absolute;
  top: calc(env(safe-area-inset-top, 0px) + 8px);
  right: calc(env(safe-area-inset-right, 0px) + 8px);
  background: rgba(0, 0, 0, 0.6);
  color: #fff;
  border: 2px solid #444;
  padding: 6px 10px;
  font-size: 12px;
  font-family: inherit;
  z-index: 10;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

#mute-btn.on {
  border-color: #2a2;
  color: #8f8;
}

#mute-btn.off {
  border-color: #a22;
  color: #f88;
}