.presentation-book{position:relative;margin:0 2%;padding:64px 0 40px;border-top:var(--case-line-width) solid var(--case-line);background:radial-gradient(ellipse at 50% 45%,rgba(0,224,190,.23) 0%,rgba(0,158,130,.15) 36%,rgba(0,85,69,.07) 60%,transparent 79%);overflow:hidden;--turn-time:900ms}
.book-stage{position:relative;width:84%;max-width:min(1100px,calc(66svh * 1190 / 842));aspect-ratio:1190/842;margin:auto;perspective:2400px;touch-action:pan-y;outline:none;cursor:grab;-webkit-user-select:none;user-select:none}
.book-stage:active{cursor:grabbing}.book-stage:focus-visible{outline:1px solid #00dcc3;outline-offset:16px}
.book-volume{position:absolute;inset:0;transform:translateX(-25%);transform-style:preserve-3d;transition:transform var(--turn-time) cubic-bezier(.3,.65,.2,1)}
.book-volume.is-open{transform:translateX(0)}.book-volume.is-closed-back{transform:translateX(25%)}
.book-sheet{position:absolute;left:50%;top:0;width:50%;height:100%;transform-origin:0 50%;transform-style:preserve-3d;transition:transform var(--turn-time) cubic-bezier(.3,.65,.2,1);transform:rotateY(0deg)}
.book-sheet.is-turned{transform:rotateY(-180deg)}
.book-face{position:absolute;inset:0;background:#020807;backface-visibility:hidden;-webkit-backface-visibility:hidden;overflow:hidden;border-radius:1px 3px 3px 1px;box-shadow:none}
.book-face img{display:block;width:100%;height:100%;object-fit:cover;pointer-events:none}
.book-face:after{content:"";position:absolute;inset:0;pointer-events:none;box-sizing:border-box;border:1px solid rgba(255,255,255,.1);background:linear-gradient(90deg,rgba(0,0,0,.32) 0%,rgba(0,0,0,.21) 3%,rgba(0,0,0,.1) 7%,rgba(0,0,0,.035) 12%,transparent 20%)}
.book-back{transform:rotateY(180deg);border-radius:3px 1px 1px 3px;box-shadow:none}
.book-back:after{background:linear-gradient(270deg,rgba(0,0,0,.32) 0%,rgba(0,0,0,.21) 3%,rgba(0,0,0,.1) 7%,rgba(0,0,0,.035) 12%,transparent 20%)}
.book-sheet.is-dragging{transition:none}
.book-controls{display:flex;align-items:center;justify-content:center;gap:24px;margin:40px auto 0;position:relative;z-index:10}
.book-controls button{border:1px solid #ffffff24;background:#151a18;color:#00e7c6;width:42px;height:42px;border-radius:50%;font:24px/1 Arial;cursor:pointer;transition:background .2s,opacity .2s}
.book-controls button:hover:not(:disabled){background:#18382d}.book-controls button:disabled{opacity:.25;cursor:default}.book-controls button:focus-visible{outline:2px solid #00e7c6;outline-offset:4px}
.book-counter{font-size:13px;line-height:20px;color:#a7b9b2;min-width:170px;text-align:center;font-variant-numeric:tabular-nums}
.book-hint{font-size:12px;line-height:18px;color:#698078;text-align:center;margin:14px 20px 0}
@media(max-width:639px){.presentation-book{padding:36px 0 28px}.book-stage{width:92%}.book-controls{margin-top:28px;gap:16px}.book-counter{font-size:11px;min-width:140px}.book-controls button{width:36px;height:36px}.book-hint{font-size:10px}}
@media(prefers-reduced-motion:reduce){.presentation-book{--turn-time:1ms}.book-sheet,.book-volume{transition:none}}

/* The rig tilts independently from opening and closing the book. */
.book-rig{position:absolute;inset:0;transform-style:preserve-3d;will-change:transform}
.book-curl{display:none;position:absolute;inset:0;transform-style:preserve-3d;pointer-events:none}
.book-curl span{position:absolute;top:0;height:100%;background-repeat:no-repeat;backface-visibility:hidden}
.book-face.has-curl{overflow:visible;transform-style:preserve-3d}
.book-face.has-curl .book-curl{display:block}
.book-front.has-curl>img{clip-path:inset(0 22% 0 0)}
.book-back.has-curl>img{clip-path:inset(0 0 0 22%)}
.book-front.has-curl{background:linear-gradient(90deg,#020807 78%,transparent 78%);box-shadow:none}
.book-back.has-curl{background:linear-gradient(90deg,transparent 22%,#020807 22%);box-shadow:none}
.book-face.has-curl:after{opacity:calc(1 - var(--curl-shadow,0))}
@media(prefers-reduced-motion:reduce){.book-rig{transform:none!important}.book-curl{display:none!important}}

/* Navigation matches the dark, rounded Threat Zone arrow plates. */
.book-controls button{width:32px;height:32px;border:0;border-radius:8px;background:#191c1b;color:#fff;display:grid;place-items:center;padding:8px}
.book-controls button svg{display:block;width:16px;height:16px;flex:none}
.book-controls .book-next svg{transform:rotate(180deg)}
.book-controls button:hover:not(:disabled){background:#272b29}
.book-controls button:disabled{opacity:.25}
@media(max-width:639px){.book-controls button{width:24px;height:24px;border-radius:6px;padding:6px}.book-controls button svg{width:12px;height:12px}}