/* ═══════════════════════════════════════════════════════════
   book.css — LittleTurtleryBook styles for Little Turtlery
   Requires: public-layout.css (tokens, reset, nav, footer)
   Covers:   index listing page + chapter reading page
   BEM prefix: bk-
   ═══════════════════════════════════════════════════════════ */

/* ─── Reading Progress Bar (show page only) ──────────────────
   Thin 3px bar anchored at top of viewport, just below nav.
   Width driven by inline JS scroll listener.
   ─────────────────────────────────────────────────────────── */
.bk-progress-bar {
    position: fixed;
    top: var(--nav-h);
    left: 0;
    right: 0;
    height: 3px;
    background: var(--lt-border-light);
    z-index: 90;
    pointer-events: none;
}

.bk-progress-bar__fill {
    height: 100%;
    background: linear-gradient(to right, var(--lt-sage-dark), var(--lt-sage));
    width: 0%;
    transition: width .08s linear;
}

/* ═══════════════════════════════════════════════════════════
   INDEX PAGE
   ═══════════════════════════════════════════════════════════ */

/* ─── Index Hero ─────────────────────────────────────────── */
.bk-hero {
    background: var(--lt-cream);
    padding-top: calc(var(--nav-h) + var(--sp-3xl));
    padding-bottom: var(--sp-2xl);
    text-align: center;
    position: relative;
    overflow: hidden;
}

/* Soft radial green glow behind title */
.bk-hero::before {
    content: '';
    position: absolute;
    top: 40%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 640px;
    height: 640px;
    border-radius: 50%;
    background: radial-gradient(circle, var(--lt-sage-light) 0%, transparent 68%);
    pointer-events: none;
}

.bk-hero__inner {
    position: relative;
    z-index: 1;
    max-width: 620px;
    margin-inline: auto;
}

.bk-hero__ornament {
    font-size: 26px;
    color: var(--lt-sage);
    opacity: .5;
    margin-bottom: var(--sp-md);
    line-height: 1;
}

.bk-hero__title {
    font-size: clamp(40px, 5vw, 56px);
    font-weight: var(--fw-semibold);
    color: var(--lt-ink);
    line-height: 1.15;
    text-wrap: balance;
    max-width: 20ch;
    margin-inline: auto;
    margin-top: var(--sp-sm);
    margin-bottom: var(--sp-md);
}

.bk-hero__intro {
    font-size: clamp(14px, 1.4vw, 16px);
    color: var(--lt-text-soft);
    font-weight: var(--fw-light);
    line-height: 1.9;
    max-width: 480px;
    margin-inline: auto;
    margin-bottom: var(--sp-xl);
}

/* Stats row — mirrors gallery hero stats for system consistency */
.bk-hero__stats {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--sp-xl);
    flex-wrap: wrap;
}

.bk-hero__stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2px;
}

.bk-hero__stat-num {
    font-size: 24px;
    font-weight: var(--fw-semibold);
    color: var(--lt-sage-dark);
    line-height: 1;
    letter-spacing: -.01em;
}

.bk-hero__stat-label {
    font-size: 12px;
    font-weight: var(--fw-medium);
    letter-spacing: .1em;
    text-transform: uppercase;
    color: var(--lt-text-muted);
}

.bk-hero__stat-divider {
    width: 1px;
    height: 28px;
    background: var(--lt-border);
    flex-shrink: 0;
}

/* ─── Chapters Section ───────────────────────────────────── */
.bk-chapters {
    background: var(--lt-white);
}

/* 2-column editorial grid — generous gap for breathing room */
.bk-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--sp-xl);
}

/* ─── Chapter Card ───────────────────────────────────────── */
.bk-card {
    border-radius: var(--r-lg);
    overflow: hidden;
    background: var(--lt-cream);
    border: 1px solid var(--lt-border-light);
    transition: box-shadow var(--ease), transform var(--ease);
}

.bk-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-5px);
}

/* Anchor wraps the entire card (frame + body) */
.bk-card__link {
    display: flex;
    flex-direction: column;
    height: 100%;
    text-decoration: none;
    color: inherit;
    -webkit-tap-highlight-color: transparent;
}

/* Portrait cover frame — 3:4 ratio for book cover proportions */
.bk-card__frame {
    position: relative;
    aspect-ratio: 3 / 4;
    overflow: hidden;
    flex-shrink: 0;
}

.bk-card__cover {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
    transition: transform .65s ease;
}

.bk-card:hover .bk-card__cover {
    transform: scale(1.04);
}

/* Large emoji icon shown when no cover image */
.bk-card__placeholder-icon {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 56px;
    opacity: .3;
    user-select: none;
    pointer-events: none;
}

/* Two-layer gradient overlay for text legibility */
.bk-card__overlay {
    position: absolute;
    inset: 0;
    background: linear-gradient(
        to top,
        rgba(0, 0, 0, .60) 0%,
        rgba(0, 0, 0, .08) 48%,
        rgba(0, 0, 0, 0)   100%
    );
    pointer-events: none;
}

/* Badge cluster — top-left of the cover frame */
.bk-card__badges {
    position: absolute;
    top: 14px;
    left: 14px;
    display: flex;
    flex-direction: column;
    gap: 6px;
    z-index: 2;
}

.bk-card__badge {
    display: inline-block;
    padding: 3px 10px;
    border-radius: var(--r-full);
    font-size: 11px;
    font-weight: var(--fw-medium);
    letter-spacing: .05em;
    white-space: nowrap;
    backdrop-filter: blur(6px);
    -webkit-backdrop-filter: blur(6px);
}

.bk-card__badge--chapter {
    background: rgba(255, 255, 255, .20);
    color: rgba(255, 255, 255, .90);
    border: 1px solid rgba(255, 255, 255, .28);
}

.bk-card__badge--featured {
    background: var(--lt-sage);
    color: #fff;
}

/* Card body — text content below the cover frame */
.bk-card__body {
    padding: var(--sp-lg) var(--sp-lg) var(--sp-md);
    display: flex;
    flex-direction: column;
    gap: 8px;
    flex: 1;
}

/* Stone name — small allcaps label */
.bk-card__stone {
    font-size: 11px;
    font-weight: var(--fw-semibold);
    letter-spacing: .14em;
    text-transform: uppercase;
    color: var(--lt-sage-dark);
}

.bk-card__title {
    font-size: clamp(17px, 1.8vw, 21px);
    font-weight: var(--fw-semibold);
    color: var(--lt-ink);
    line-height: 1.3;
}

.bk-card__intro {
    font-size: 14px;
    color: var(--lt-text-soft);
    font-weight: var(--fw-light);
    line-height: 1.8;
    flex: 1;
}

/* Card footer: time · pages + read CTA */
.bk-card__footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-top: var(--sp-sm);
    border-top: 1px solid var(--lt-border-light);
    margin-top: auto;
}

.bk-card__meta {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 13px;
    color: var(--lt-text-muted);
    font-weight: var(--fw-regular);
}

.bk-card__meta-dot {
    opacity: .4;
}

.bk-card__cta {
    font-size: 13px;
    font-weight: var(--fw-medium);
    color: var(--lt-sage-dark);
    white-space: nowrap;
}

/* ─── Featured Card — full-width treatment ───────────────── */
.bk-card--featured {
    grid-column: 1 / -1;   /* span both columns */
}

/* Landscape proportions when featured spans full width */
.bk-card--featured .bk-card__link {
    flex-direction: row;
    align-items: stretch;
}

.bk-card--featured .bk-card__frame {
    width: 45%;
    aspect-ratio: unset;
    flex-shrink: 0;
}

.bk-card--featured .bk-card__body {
    padding: var(--sp-xl) var(--sp-xl) var(--sp-lg);
    justify-content: center;
}

.bk-card--featured .bk-card__title {
    font-size: clamp(20px, 2.5vw, 28px);
}

.bk-card--featured .bk-card__intro {
    font-size: 15px;
    line-height: 1.85;
}

/* ═══════════════════════════════════════════════════════════
   SHOW / READING PAGE
   ═══════════════════════════════════════════════════════════ */

/* ─── Chapter Header ─────────────────────────────────────── */
.bk-chapter-header {
    position: relative;
    background: var(--lt-stone-xlight);
    padding-top: calc(var(--nav-h) + var(--sp-3xl));
    padding-bottom: var(--sp-3xl);
    text-align: center;
    overflow: hidden;
}

/*
  Stone-specific gradient wash — inline style sets background.
  Opacity .06 gives a whisper of the stone's character
  without disrupting the type.
*/
.bk-chapter-header__gradient-wash {
    position: absolute;
    inset: 0;
    opacity: .06;
    pointer-events: none;
}

/* Back link — top-left, above nav padding */
.bk-chapter-header__back {
    position: absolute;
    top: calc(var(--nav-h) + var(--sp-lg));
    left: clamp(16px, 4vw, 40px);
    font-size: 13px;
    font-weight: var(--fw-medium);
    color: var(--lt-text-muted);
    text-decoration: none;
    letter-spacing: .01em;
    transition: color var(--ease);
    display: inline-flex;
    align-items: center;
    gap: 5px;
    z-index: 2;
}

.bk-chapter-header__back:hover {
    color: var(--lt-sage-dark);
}

.bk-chapter-header__inner {
    position: relative;
    z-index: 1;
    max-width: 680px;
    margin-inline: auto;
}

/* Chapter label pill */
.bk-chapter-header__label {
    display: inline-block;
    background: var(--lt-sage-light);
    color: var(--lt-sage-dark);
    font-size: 12px;
    font-weight: var(--fw-semibold);
    letter-spacing: .14em;
    text-transform: uppercase;
    padding: 5px 18px;
    border-radius: var(--r-full);
    margin-bottom: var(--sp-lg);
}

/* Stone name — small allcaps, stone-gold accent */
.bk-chapter-header__stone {
    font-size: 13px;
    font-weight: var(--fw-medium);
    letter-spacing: .14em;
    text-transform: uppercase;
    color: var(--lt-stone-dark);
    margin-bottom: var(--sp-sm);
}

.bk-chapter-header__title {
    font-size: clamp(28px, 5vw, 52px);
    font-weight: var(--fw-semibold);
    color: var(--lt-ink);
    line-height: 1.15;
    margin-bottom: var(--sp-md);
    white-space: pre-line;
}

.bk-chapter-header__subtitle {
    font-size: clamp(14px, 1.5vw, 17px);
    color: var(--lt-text-soft);
    font-weight: var(--fw-light);
    line-height: 1.7;
    max-width: 480px;
    margin-inline: auto;
    margin-bottom: var(--sp-xl);
}

/* Reading meta — time · pages */
.bk-chapter-header__meta {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    font-size: 13px;
    color: var(--lt-text-muted);
    font-weight: var(--fw-regular);
}

.bk-chapter-header__meta-dot {
    opacity: .4;
}

/* ─── Intro Section ──────────────────────────────────────── */
.bk-intro {
    background: var(--lt-white);
    padding-block: var(--sp-2xl);   /* tighter: 52px vs 80px for a short text + rule */
}

.bk-intro__inner {
    max-width: 580px;
    margin-inline: auto;
    text-align: center;
}

.bk-intro__text {
    font-size: clamp(15px, 1.6vw, 18px);
    color: var(--lt-text-soft);
    font-weight: var(--fw-light);
    line-height: 2.05;
    font-style: italic;
}

/* Ornamental rule below intro — signals transition to pages */
.bk-intro__rule {
    width: 36px;
    height: 1.5px;
    background: var(--lt-sage);
    margin: var(--sp-xl) auto 0;
    opacity: .55;
}

/* ─── Reader Section ─────────────────────────────────────── */
.bk-reader-section {
    background: var(--lt-cream);
    padding-block: var(--sp-3xl);
}

/*
  Centered reading column — max 600px.
  This constrains all page images to a comfortable reading width:
  - Desktop: 600px centered in a 1200px container
  - Mobile: full gutter-width (natural flow)
*/
.bk-reader {
    max-width: 600px;
    margin-inline: auto;
}

/* ─── Individual Page ────────────────────────────────────── */
.bk-page {
    margin-bottom: var(--sp-3xl);
}

.bk-page:last-child {
    margin-bottom: 0;
}

/*
  Image wrapper — relative positioning enables the watermark overlay.
  border-radius + overflow clips both image and watermark together.
*/
.bk-page__wrap {
    position: relative;
    display: block;
    border-radius: var(--r-md);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    background: var(--lt-border-light);  /* visible while image loads */
}

/* Natural portrait image — width fills the reading column */
.bk-page__img {
    display: block;
    width: 100%;
    height: auto;
}

/* ─── Watermark ───────────────────────────────────────────────
   Design decisions:
   · Positioned bottom-right — avoids center/top content areas
   · font-size 10px, letter-spacing .22em — minimal footprint
   · color rgba(255,255,255,.38) — subtle on dark images
   · text-shadow 0 1px 0 rgba(0,0,0,.6) — legible on light images
   · user-select + pointer-events none — non-interactive
   · Configurable: global → chapter → page cascade (see BookData)
   ─────────────────────────────────────────────────────────── */
.bk-page__watermark {
    position: absolute;
    bottom: 14px;
    right: 16px;
    font-family: var(--font);
    font-size: 10px;
    font-weight: var(--fw-medium);
    letter-spacing: .22em;
    text-transform: uppercase;
    color: rgba(255, 255, 255, .38);
    text-shadow:
        0 1px 0  rgba(0, 0, 0, .65),
        0 0 10px rgba(0, 0, 0, .25);
    user-select: none;
    pointer-events: none;
    z-index: 3;
    white-space: nowrap;
    line-height: 1;
}

/* Page number — centered below each image */
.bk-page__num {
    text-align: center;
    font-size: 12px;
    color: var(--lt-text-muted);
    font-weight: var(--fw-regular);
    letter-spacing: .05em;
    margin-top: var(--sp-md);
}

/* Slim ornamental separator between pages */
.bk-page-sep {
    width: 24px;
    height: 1px;
    background: var(--lt-border);
    margin: 0 auto var(--sp-3xl);
    opacity: .45;
}

/* ─── Chapter End ────────────────────────────────────────── */
.bk-end {
    background: var(--lt-stone-xlight);
    padding-block: var(--sp-3xl);
    text-align: center;
    border-top: 1px solid var(--lt-border-light);
}

.bk-end__inner {
    max-width: 420px;
    margin-inline: auto;
}

.bk-end__ornament {
    display: block;
    font-size: 22px;
    color: var(--lt-sage);
    opacity: .5;
    margin-bottom: var(--sp-lg);
    line-height: 1;
}

.bk-end__label {
    font-size: 11px;
    font-weight: var(--fw-semibold);
    letter-spacing: .20em;
    text-transform: uppercase;
    color: var(--lt-text-muted);
    margin-bottom: 6px;
}

.bk-end__chapter {
    font-size: 20px;
    font-weight: var(--fw-semibold);
    color: var(--lt-ink);
    margin-bottom: var(--sp-sm);
}

.bk-end__stone {
    font-size: 12px;
    color: var(--lt-stone-dark);
    font-weight: var(--fw-medium);
    letter-spacing: .12em;
    text-transform: uppercase;
}

/* Closing reflective quote below the stone name */
.bk-end__thought {
    font-size: 15px;
    font-style: italic;
    color: var(--lt-text-soft);
    font-weight: var(--fw-light);
    line-height: 1.9;
    max-width: 380px;
    margin: var(--sp-lg) auto 0;
    border-top: 1px solid var(--lt-border-light);
    padding-top: var(--sp-lg);
}

/* ─── Prev / Next Chapter Navigation ────────────────────── */
.bk-nav {
    background: var(--lt-white);
    padding-block: var(--sp-2xl);
    border-top: 1px solid var(--lt-border-light);
}

.bk-nav__inner {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--sp-lg);
}

.bk-nav__card {
    display: flex;
    align-items: stretch;
    border-radius: var(--r-md);
    overflow: hidden;
    border: 1px solid var(--lt-border-light);
    text-decoration: none;
    color: inherit;
    background: var(--lt-cream);
    transition: box-shadow var(--ease), transform var(--ease);
    -webkit-tap-highlight-color: transparent;
    min-height: 88px;
}

.bk-nav__card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-3px);
}

/* Coloured accent strip from the stone's gradient */
.bk-nav__card-accent {
    width: 5px;
    flex-shrink: 0;
}

/* Next card: accent strip on right side */
.bk-nav__card--next .bk-nav__card-accent {
    order: 2;
}

.bk-nav__card-body {
    padding: var(--sp-md) var(--sp-lg);
    display: flex;
    flex-direction: column;
    gap: 4px;
    flex: 1;
    min-width: 0;
}

/* Next: right-aligned text */
.bk-nav__card--next .bk-nav__card-body {
    text-align: right;
}

.bk-nav__direction {
    font-size: 11px;
    font-weight: var(--fw-semibold);
    letter-spacing: .14em;
    text-transform: uppercase;
    color: var(--lt-text-muted);
}

.bk-nav__chapter-label {
    font-size: 12px;
    color: var(--lt-sage-dark);
    font-weight: var(--fw-medium);
}

.bk-nav__chapter-title {
    font-size: 15px;
    font-weight: var(--fw-semibold);
    color: var(--lt-ink);
    line-height: 1.3;
    margin: 0;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* Back-to-index row below the nav cards */
.bk-nav__back {
    text-align: center;
    margin-top: var(--sp-lg);
}

.bk-nav__back-link {
    font-size: 13px;
    font-weight: var(--fw-medium);
    color: var(--lt-text-muted);
    text-decoration: none;
    letter-spacing: .02em;
    transition: color var(--ease);
}

.bk-nav__back-link:hover {
    color: var(--lt-sage-dark);
}

/* ─── Related Chapters ───────────────────────────────────── */
.bk-related {
    background: var(--lt-cream);
    padding-block: var(--sp-3xl);
}

.bk-related__grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--sp-lg);
}

/* Related card — compact version with landscape cover */
.bk-related-card {
    border-radius: var(--r-md);
    overflow: hidden;
    background: var(--lt-white);
    border: 1px solid var(--lt-border-light);
    text-decoration: none;
    color: inherit;
    display: block;
    transition: box-shadow var(--ease), transform var(--ease);
    -webkit-tap-highlight-color: transparent;
}

.bk-related-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-4px);
}

/* Landscape frame — allows 3 cards to sit side by side without being too tall */
.bk-related-card__frame {
    aspect-ratio: 4 / 3;
    position: relative;
    overflow: hidden;
}

.bk-related-card__gradient {
    position: absolute;
    inset: 0;
}

.bk-related-card__cover {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform .55s ease;
}

.bk-related-card:hover .bk-related-card__cover {
    transform: scale(1.05);
}

/* Bottom gradient overlay */
.bk-related-card__overlay {
    position: absolute;
    inset: 0;
    background: linear-gradient(to top, rgba(0,0,0,.55) 0%, transparent 60%);
    pointer-events: none;
}

/* Chapter label in bottom-left of frame */
.bk-related-card__chapter {
    position: absolute;
    bottom: 10px;
    left: 12px;
    font-size: 10px;
    font-weight: var(--fw-semibold);
    letter-spacing: .10em;
    text-transform: uppercase;
    color: rgba(255, 255, 255, .80);
    z-index: 1;
}

.bk-related-card__body {
    padding: 13px 14px 16px;
}

.bk-related-card__stone {
    font-size: 11px;
    font-weight: var(--fw-semibold);
    letter-spacing: .12em;
    text-transform: uppercase;
    color: var(--lt-sage-dark);
    margin-bottom: 4px;
}

.bk-related-card__title {
    font-size: 14px;
    font-weight: var(--fw-medium);
    color: var(--lt-ink);
    line-height: 1.35;
    margin: 0;
}

/* ─── Responsive — tablet ────────────────────────────────── */
@media (max-width: 900px) {
    .bk-grid {
        gap: var(--sp-lg);
    }

    .bk-related__grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* ─── Responsive — mobile ────────────────────────────────── */
@media (max-width: 640px) {
    /* Book hero: tighter top padding on mobile */
    .bk-hero {
        padding-top: calc(var(--nav-h) + var(--sp-2xl));
    }

    /* Cards become horizontal on mobile (image-left, text-right)
       to avoid oversized portrait frames in a single column */
    .bk-grid {
        grid-template-columns: 1fr;
        gap: var(--sp-md);
    }

    .bk-card__link {
        flex-direction: row;
        align-items: stretch;
    }

    .bk-card__frame {
        width: 110px;
        aspect-ratio: unset;   /* height driven by sibling content */
        flex-shrink: 0;
    }

    .bk-card__placeholder-icon {
        font-size: 30px;
    }

    /* Featured card: revert to standard portrait layout on mobile */
    .bk-card--featured .bk-card__link {
        flex-direction: row;    /* keep horizontal (inherits from mobile .bk-card__link) */
    }

    .bk-card--featured .bk-card__frame {
        width: 110px;           /* same as regular mobile card */
    }

    .bk-card--featured .bk-card__body {
        padding: var(--sp-md) var(--sp-md) var(--sp-sm);
        justify-content: flex-start;
    }

    .bk-card--featured .bk-card__title {
        font-size: clamp(17px, 1.8vw, 21px);   /* reset to base card size */
    }

    .bk-card--featured .bk-card__intro {
        font-size: 14px;
    }

    /* Chapter header: slightly tighter on mobile */
    .bk-chapter-header__back {
        top: calc(var(--nav-h) + var(--sp-md));
        font-size: 12px;
    }

    /* Nav: stack prev/next vertically on mobile */
    .bk-nav__inner {
        grid-template-columns: 1fr;
    }

    .bk-nav__card--next .bk-nav__card-body {
        text-align: left;
    }

    .bk-nav__card--next .bk-nav__card-accent {
        order: 0;              /* accent strip back to left side */
    }

    /* Related: 2-col stays fine at mobile widths */
    .bk-related__grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--sp-sm);
    }

    /* Hero stats: tighten gap */
    .bk-hero__stats {
        gap: var(--sp-lg);
    }

    .bk-hero__stat-divider {
        height: 22px;
    }
}

/* Very small screens */
@media (max-width: 400px) {
    .bk-related__grid {
        grid-template-columns: 1fr;
    }

    /* Watermark: slightly smaller on very small viewports */
    .bk-page__watermark {
        font-size: 9px;
        letter-spacing: .16em;
        bottom: 10px;
        right: 12px;
    }
}