* { box-sizing: border-box; }
html, body { width:100%; height:100%; margin:0; overflow:hidden; background:#fff; }
body { position:fixed; inset:0; overscroll-behavior:none; touch-action:pan-y; -webkit-user-select:none; user-select:none; }
#book { position:fixed; inset:0; overflow:hidden; background:#fff; touch-action:pan-y; }
#track { height:100%; display:flex; will-change:transform; transform:translate3d(0,0,0); }
.page { flex:0 0 100vw; width:100vw; height:100%; display:flex; align-items:center; justify-content:center; overflow:hidden; background:#fff; }
.page img { width:100%; height:100%; object-fit:contain; display:block; pointer-events:none; -webkit-user-drag:none; }

#page-controls {
  position: fixed;
  left: 0;
  right: 0;
  bottom: calc(18px + env(safe-area-inset-bottom));
  z-index: 1000;
  pointer-events: none;
}
.page-button {
  position: absolute;
  bottom: 0;
  width: 54px;
  height: 54px;
  padding: 0;
  border: 0;
  border-radius: 50%;
  background: rgba(255,255,255,.94);
  color: #222;
  box-shadow: 0 2px 10px rgba(0,0,0,.22);
  display: flex;
  align-items: center;
  justify-content: center;
  font: 600 30px/1 Arial, sans-serif;
  cursor: pointer;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  pointer-events: auto;
}
#prev-page { left: calc(18px + env(safe-area-inset-left)); }
#next-page { right: calc(18px + env(safe-area-inset-right)); }
.page-button:active { transform: scale(.94); }