/* Shared page chrome for every game: full-screen centred canvas plus corner buttons. */
* { box-sizing: border-box; }
html, body {
  margin: 0;
  height: 100%;
  overflow: hidden;
  overscroll-behavior: none;
  touch-action: none;
  -webkit-user-select: none;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}
body {
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: Inter, system-ui, sans-serif;
}
canvas { display: block; touch-action: none; }
.shell-buttons {
  position: fixed;
  top: max(10px, env(safe-area-inset-top));
  left: 10px;
  right: 10px;
  display: flex;
  justify-content: space-between;
  pointer-events: none;
  z-index: 10;
}
.shell-btn {
  pointer-events: auto;
  width: 40px;
  height: 40px;
  border-radius: 12px;
  border: none;
  background: rgba(0, 0, 0, .45);
  color: #fff;
  font-size: 20px;
  line-height: 40px;
  text-align: center;
  text-decoration: none;
  cursor: pointer;
}
.shell-btn.off { opacity: .4; }