/* ============================================================
   bvb.dev — Monograph Stylesheet
   Colors:
     #F4EFE6 — Laid paper background
     #1A1612 — Ink black (primary text)
     #2C2822 — Body text (slightly lighter ink)
     #8C7E72 — Aged annotation (marginalia, footnotes)
     #5C4E42 — Medium brown (epigraphs, secondary)
     #C8B89A — Antique rule (dividers, accents)
   Fonts:
     Commissioner (100–900) — primary
     Libre Baskerville (400, 400i) — epigraphs, footnotes
   ============================================================ */

/* ---- Color Reference (all palette colors) ---- */
/* #F4EFE6 #1A1612 #2C2822 #8C7E72 #5C4E42 #C8B89A #000000 */

/* ---- Reset & Base ---- */

*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    background-color: #F4EFE6;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='400' height='400'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.75' numOctaves='4' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='400' height='400' filter='url(%23n)' opacity='0.04'/%3E%3C/svg%3E");
    color: #2C2822;
    font-family: 'Commissioner', sans-serif;
    font-weight: 300;
    font-size: 15px;
    line-height: 26px;
    letter-spacing: 0.02em;
    min-height: 100vh;
}

/* ---- CSS Custom Properties ---- */

:root {
    --col-width: 58ch;
    --margin-col-width: 220px;
    --spine-width: 24px;
    --col-left: 28vw;
    --col-left-mobile: 5vw;
    --color-paper: #F4EFE6;
    --color-ink: #1A1612;
    --color-body: #2C2822;
    --color-annotation: #8C7E72;
    --color-secondary: #5C4E42;
    --color-rule: #C8B89A;
    --color-pure-black: #000000;
    --fade-duration: 900ms;
    --fade-ease: cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

/* ---- Spine Navigation ---- */

.spine {
    position: fixed;
    left: 0;
    top: 0;
    width: var(--spine-width);
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
    border-right: 1px solid var(--color-rule);
}

.spine-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 20px;
    padding: 0;
}

.spine-item {
    display: flex;
    align-items: center;
    justify-content: center;
}

.spine-numeral {
    font-family: 'Commissioner', sans-serif;
    font-weight: 100;
    font-size: 9px;
    color: var(--color-rule);
    letter-spacing: 0.06em;
    text-transform: uppercase;
    transition: color 300ms ease;
    cursor: default;
    writing-mode: vertical-rl;
    text-orientation: mixed;
}

.spine-item.active .spine-numeral {
    color: var(--color-annotation);
}

/* ---- Document Layout ---- */

.document {
    padding-left: var(--col-left);
    padding-right: 8vw;
    padding-top: 120px;
    padding-bottom: 80px;
    max-width: calc(var(--col-left) + var(--col-width) + 8vw);
}

article {
    position: relative;
}

/* ---- Section Layout ---- */

.section {
    display: grid;
    grid-template-columns: var(--margin-col-width) 1fr;
    gap: 0 48px;
    margin-bottom: 80px;
    opacity: 0;
    filter: blur(6px);
    transition:
        opacity var(--fade-duration) var(--fade-ease),
        filter var(--fade-duration) var(--fade-ease);
}

.section.visible {
    opacity: 1;
    filter: blur(0);
}

.section-margin {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    padding-top: 4px;
    position: relative;
}

.section-body {
    max-width: var(--col-width);
}

/* ---- Running Head (margin label) ---- */

.running-head {
    font-family: 'Commissioner', sans-serif;
    font-weight: 400;
    font-size: 11px;
    line-height: 1.4;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--color-annotation);
    display: block;
    margin-bottom: 24px;
    font-variant: small-caps;
}

/* ---- Marginal Numeral ---- */

.marginal-numeral {
    font-family: 'Commissioner', sans-serif;
    font-weight: 100;
    font-size: 36px;
    line-height: 1;
    color: var(--color-rule);
    display: block;
    margin-bottom: 16px;
}

/* ---- Margin Note ---- */

.margin-note {
    font-family: 'Commissioner', sans-serif;
    font-weight: 400;
    font-size: 11px;
    line-height: 18px;
    color: var(--color-annotation);
    letter-spacing: 0.02em;
    margin-top: 16px;
}

/* ---- Body Text ---- */

.section-body p {
    font-family: 'Commissioner', sans-serif;
    font-weight: 300;
    font-size: 15px;
    line-height: 26px;
    letter-spacing: 0.02em;
    color: var(--color-body);
    margin-bottom: 20px;
    max-width: var(--col-width);
}

.section-body p:last-child {
    margin-bottom: 0;
}

/* ---- Section Heading (h2) ---- */

.section-heading {
    font-family: 'Commissioner', sans-serif;
    font-weight: 600;
    font-size: 28px;
    line-height: 34px;
    letter-spacing: 0;
    color: var(--color-ink);
    text-transform: none;
    font-variant: small-caps;
    margin-bottom: 32px;
}

/* ---- Chapter Statement (h1) ---- */

.chapter-statement {
    font-family: 'Commissioner', sans-serif;
    font-weight: 800;
    font-size: clamp(48px, 5.5vw, 64px);
    line-height: 1.05;
    letter-spacing: -0.01em;
    color: var(--color-ink);
    max-width: var(--col-width);
}

/* ---- Chapter Statement Section Override ---- */

.section--statement {
    align-items: start;
}

.section--statement .section-margin {
    padding-top: 8px;
}

/* ---- Section Rule Divider ---- */

.section-rule {
    border: none;
    border-top: 1px solid var(--color-rule);
    width: 40%;
    margin-left: var(--col-left);
    margin-bottom: 80px;
    opacity: 0;
    transition: opacity var(--fade-duration) var(--fade-ease);
}

.section-rule.visible {
    opacity: 1;
}

/* ---- Block Quotation (Epigraph) ---- */

.block-quote {
    border: none;
    padding: 0;
    margin: 0 0 28px 0;
    max-width: var(--col-width);
}

.block-quote p {
    font-family: 'Libre Baskerville', serif;
    font-weight: 400;
    font-style: italic;
    font-size: 14px;
    line-height: 24px;
    color: var(--color-secondary);
    letter-spacing: 0;
    margin-bottom: 14px;
}

.block-quote p:last-of-type {
    margin-bottom: 16px;
}

.quote-attribution {
    display: block;
    font-family: 'Commissioner', sans-serif;
    font-weight: 400;
    font-size: 11px;
    line-height: 18px;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: var(--color-annotation);
    font-style: normal;
    margin-top: 8px;
}

/* ---- Footnote text ---- */

.footnote {
    font-family: 'Libre Baskerville', serif;
    font-weight: 400;
    font-size: 11px;
    line-height: 18px;
    color: var(--color-annotation);
    max-width: var(--col-width);
    margin-top: 16px;
    padding-top: 16px;
    border-top: 1px solid var(--color-rule);
    width: 40%;
}

/* ---- Links ---- */

a {
    color: inherit;
    font-weight: 600;
    text-decoration: underline;
    text-decoration-color: var(--color-rule);
    text-underline-offset: 3px;
    transition: text-decoration-color 200ms ease;
}

a:hover {
    text-decoration-color: var(--color-annotation);
}

/* ---- Footer ---- */

.site-footer {
    margin-left: var(--col-left);
    padding: 40px 0 60px;
    border-top: 1px solid var(--color-rule);
    width: var(--col-width);
    max-width: var(--col-width);
}

.footer-text {
    font-family: 'Commissioner', sans-serif;
    font-weight: 400;
    font-size: 11px;
    line-height: 18px;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--color-annotation);
    font-variant: small-caps;
}

/* ---- Dense text section specifics ---- */

.section--dense .section-margin {
    padding-top: 6px;
}

/* ---- Epigraph section ---- */

.section--epigraph .section-body {
    padding-left: 24px;
    border-left: 1px solid var(--color-rule);
}

/* ---- Closing section ---- */

.section--closing .section-body p:last-child {
    font-weight: 400;
    font-style: normal;
    color: var(--color-ink);
}

/* ---- Responsive: Tablet ---- */

@media (max-width: 1100px) {
    :root {
        --col-left: 18vw;
        --margin-col-width: 160px;
    }

    .document {
        padding-left: var(--col-left);
        padding-right: 5vw;
    }

    .section-rule {
        margin-left: var(--col-left);
    }

    .site-footer {
        margin-left: var(--col-left);
    }
}

/* ---- Responsive: Mobile ---- */

@media (max-width: 720px) {
    :root {
        --col-left: var(--col-left-mobile);
        --margin-col-width: 0px;
    }

    .spine {
        display: none;
    }

    .document {
        padding-left: var(--col-left-mobile);
        padding-right: var(--col-left-mobile);
        padding-top: 60px;
    }

    .section {
        grid-template-columns: 1fr;
        gap: 0;
    }

    .section-margin {
        display: flex;
        flex-direction: row;
        align-items: baseline;
        gap: 12px;
        margin-bottom: 12px;
    }

    .marginal-numeral {
        font-size: 22px;
        display: none;
    }

    .margin-note {
        display: none;
    }

    .chapter-statement {
        font-size: clamp(36px, 8vw, 52px);
    }

    .section-rule {
        margin-left: var(--col-left-mobile);
        width: 50%;
    }

    .site-footer {
        margin-left: var(--col-left-mobile);
        width: auto;
    }

    .footnote {
        width: 100%;
    }

    .section--epigraph .section-body {
        padding-left: 16px;
    }
}