/* ── Paměti — Book Viewer ── */
.book-section {
    padding: 100px 0 60px;
    min-height: 100vh;
}

.book-empty {
    text-align: center;
    padding: 120px 0;
}

.book-empty h2 {
    font-family: var(--font-display);
    font-size: 36px;
    font-weight: 700;
    margin-bottom: 16px;
}

.book-empty p {
    color: var(--clr-text-dim);
    font-size: 16px;
}

.book-empty code {
    background: var(--clr-accent-subtle);
    color: var(--clr-accent);
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 14px;
}

/* ── Book wrapper ── */
.book-wrapper {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 24px;
    position: relative;
    padding: 0 24px;
}

/* ── Book (full width) ── */
.book {
    position: relative;
    width: 100%;
    aspect-ratio: 2.754;
    perspective: 2000px;
}

.book__spread {
    position: absolute;
    inset: 0;
    display: flex;
    border-radius: 3px 6px 6px 3px;
    overflow: hidden;
    box-shadow:
        2px 4px 20px rgba(0, 0, 0, 0.5),
        0 1px 3px rgba(0, 0, 0, 0.3);
    background: #1a1a1a;
    transform-style: preserve-3d;
}

.book__spine { display: none; }

.book__page {
    flex: 1;
    position: relative;
    overflow: hidden;
    background: #1a1a1a;
    cursor: zoom-in;
}

.book__page--left {
    border-right: 1px solid rgba(0, 0, 0, 0.3);
}

.book__page--right {
    position: relative;
    z-index: 2;
}

.book__page-inner {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.book__page-inner img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    display: block;
}

/* ── Spine shadow / gutter ── */
.book__page--left::after {
    content: '';
    position: absolute;
    top: 0; right: 0;
    width: 40px; height: 100%;
    background: linear-gradient(to right,
        transparent,
        rgba(0, 0, 0, 0.12) 40%,
        rgba(0, 0, 0, 0.3)
    );
    pointer-events: none;
}

.book__page--right::after {
    content: '';
    position: absolute;
    top: 0; left: 0;
    width: 40px; height: 100%;
    background: linear-gradient(to left,
        transparent,
        rgba(0, 0, 0, 0.12) 40%,
        rgba(0, 0, 0, 0.3)
    );
    pointer-events: none;
}

/* ── Flip animation layer ── */
.book__flip {
    position: absolute;
    top: 0;
    width: 50%;
    height: 100%;
    transform-style: preserve-3d;
    transform-origin: 0 50%;
    transform: rotateY(0deg);
    transition: none;
    z-index: 10;
    pointer-events: none;
    display: none;
}

.book__flip--right {
    right: 0;
    left: auto;
    transform-origin: 0 50%;  /* left edge = book center */
}

.book__flip--left {
    left: 0;
    right: auto;
    transform-origin: 100% 50%;  /* right edge = book center */
}

.book__flip.animating {
    transition: transform 0.75s cubic-bezier(0.25, 0.1, 0.25, 0.9);
}

.book__flip.flipped {
    transform: rotateY(-180deg);
}

.book__flip-front,
.book__flip-back {
    position: absolute;
    inset: 0;
    backface-visibility: hidden;
    overflow: hidden;
    background: #1a1a1a;
    -webkit-backface-visibility: hidden;
}

.book__flip-front { z-index: 2; }
.book__flip-back  { transform: rotateY(180deg); }

.book__flip-front img,
.book__flip-back img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    display: block;
}

.book__flip-front::after,
.book__flip-back::after {
    content: '';
    position: absolute;
    top: 0; left: 0;
    width: 40px; height: 100%;
    pointer-events: none;
}

.book__flip-front::after {
    background: linear-gradient(to left,
        transparent,
        rgba(0, 0, 0, 0.12) 40%,
        rgba(0, 0, 0, 0.3)
    );
}

.book__flip-back::after {
    left: auto; right: 0;
    background: linear-gradient(to right,
        transparent,
        rgba(0, 0, 0, 0.12) 40%,
        rgba(0, 0, 0, 0.3)
    );
}

/* Falling shadow during flip */
.book__flip::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(to right,
        rgba(0, 0, 0, 0.3) 0%,
        transparent 40%
    );
    z-index: 3;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.75s ease;
}

.book__flip.animating::before {
    opacity: 1;
}

/* ── Navigation ── */
.book__nav {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: var(--clr-bg-card);
    border: 1px solid var(--clr-border);
    color: var(--clr-text);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s;
    z-index: 20;
}

.book__nav:hover {
    background: var(--clr-accent);
    color: #fff;
    border-color: var(--clr-accent);
    box-shadow: 0 4px 20px var(--clr-accent-glow);
}

.book__nav:disabled {
    opacity: 0.3;
    cursor: not-allowed;
    pointer-events: none;
}

.book__nav--prev { left: 5px; }
.book__nav--next { right: 5px; }
.book__nav svg { flex-shrink: 0; }

/* ── Counter ── */
.book__counter {
    font-family: var(--font-display);
    font-size: 15px;
    color: var(--clr-text-dim);
    letter-spacing: 0.04em;
}

.book__counter span:first-child {
    color: var(--clr-accent);
    font-weight: 600;
}

/* ── Zoom overlay ── */
.zoom-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.92);
    z-index: 2000;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
}

.zoom-overlay.active {
    opacity: 1;
    pointer-events: all;
}

.zoom-overlay img {
    max-width: 95vw;
    max-height: 95vh;
    object-fit: contain;
    cursor: zoom-out;
    transform-origin: 0 0;
    transition: transform 0.1s ease;
    box-shadow: 0 8px 40px rgba(0, 0, 0, 0.6);
    border-radius: 2px;
}

.zoom-close {
    position: absolute;
    top: 24px;
    right: 24px;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    color: #fff;
    font-size: 22px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s;
    z-index: 2001;
}

.zoom-close:hover {
    background: rgba(255, 255, 255, 0.2);
}

.zoom-info {
    position: absolute;
    bottom: 24px;
    left: 50%;
    transform: translateX(-50%);
    color: rgba(255, 255, 255, 0.5);
    font-size: 13px;
    font-family: var(--font-sans);
    pointer-events: none;
}

/* ── Responsive ── */
@media (max-width: 1200px) {
    .book__nav--prev { left: 8px; }
    .book__nav--next { right: 8px; }
    .book__nav { width: 44px; height: 44px; }
}

@media (max-width: 768px) {
    .book-section { padding: 90px 0 40px; }
    .book__nav--prev { left: 4px; }
    .book__nav--next { right: 4px; }
    .book__nav {
        width: 40px; height: 40px;
        background: rgba(10, 16, 30, 0.85);
        backdrop-filter: blur(10px);
    }
    .zoom-close { top: 16px; right: 16px; width: 38px; height: 38px; }
}