.opf-book{position:relative;display:block;box-sizing:border-box;perspective:2000px;touch-action:pan-y}.opf-book--bottom,.opf-book--top{touch-action:pan-x}.opf-page{display:none;position:absolute;transform-style:preserve-3d}.opf-shadow{position:absolute;left:0;top:0;pointer-events:none}