html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  background: #111;
  overflow: hidden;
  touch-action: none;
  -webkit-user-select: none;
  user-select: none;
  font-family: 'Segoe UI', system-ui, sans-serif;
}
#game {
  display: block;
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  background: #87ceeb;
  touch-action: none;
}
.ctl {
  position: fixed;
  top: 10px;
  z-index: 10;
  width: 42px;
  height: 42px;
  border: none;
  border-radius: 8px;
  background: rgba(0,0,0,0.4);
  color: #fff;
  font-size: 22px;
  cursor: pointer;
}
.ctl:hover { background: rgba(0,0,0,0.6); }
#fs { right: 10px; }
#pause { right: 60px; }
#mute { right: 110px; }