/* ==========================================================================
   daitoua.com — Scholarly Naturalism
   ========================================================================== */

/* --- CSS Custom Properties --- */
:root {
    /* Palette */
    --darkroom-black: #0a0a0c;
    --vellum-white: #f4f0e8;
    --sumi-ink: #1a1a1e;
    --rice-paper: #ede8dc;
    --oxidized-copper: #5a7a6a;
    --temple-grey: #8a8279;
    --gold-leaf: #b89a5a;
    --ash: #3a3632;
    --night-overlay: rgba(10, 10, 12, 0.75);
    --night-toc: rgba(10, 10, 12, 0.97);

    /* Typography */
    --font-display: 'Cormorant Garamond', 'Georgia', serif;
    --font-body: 'Source Serif 4', 'Georgia', serif;
    --font-ui: 'DM Sans', 'Helvetica Neue', sans-serif;

    /* Spacing */
    --baseline: 1.5rem;

    /* Reading progress */
    --read-progress: 0;
}

/* --- Reset & Base --- */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
    overflow-x: hidden;
}

body {
    font-family: var(--font-body);
    font-weight: 400;
    color: var(--sumi-ink);
    background: var(--darkroom-black);
    line-height: 1.75;
    letter-spacing: 0.01em;
    overflow-x: hidden;
}

/* --- Grain Overlay --- */
#grain-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    pointer-events: none;
    z-index: 9999;
    opacity: 0;
    transition: opacity 400ms ease;
}

#grain-overlay svg {
    width: 100%;
    height: 100%;
}

#grain-overlay.active {
    opacity: 0.03;
}

.spread-light #grain-overlay,
.spread-dark #grain-overlay {
    mix-blend-mode: multiply;
}

/* --- Reading Progress Bar --- */
#progress-bar {
    position: fixed;
    top: 0;
    left: 0;
    height: 2px;
    width: calc(var(--read-progress) * 100%);
    background: var(--gold-leaf);
    z-index: 10001;
    transition: width 50ms linear;
}

/* --- Navigation --- */
#top-nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 clamp(1.5rem, 4vw, 3rem);
    z-index: 5000;
    opacity: 0;
    transition: opacity 600ms ease;
    background: transparent;
}

#top-nav.visible {
    opacity: 1;
}

.nav-logo {
    font-family: var(--font-ui);
    font-weight: 500;
    font-size: clamp(0.7rem, 1vw, 0.85rem);
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--rice-paper);
}

.nav-contents {
    font-family: var(--font-ui);
    font-weight: 500;
    font-size: clamp(0.7rem, 1vw, 0.85rem);
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--rice-paper);
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem 0;
    transition: color 300ms ease;
}

.nav-contents:hover {
    color: var(--gold-leaf);
}

/* --- Table of Contents Overlay --- */
#toc-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: var(--night-toc);
    z-index: 10000;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 1;
    transition: opacity 400ms ease;
}

#toc-overlay.toc-hidden {
    opacity: 0;
    pointer-events: none;
}

.toc-close-btn {
    position: absolute;
    top: 1.5rem;
    right: 2rem;
    background: none;
    border: none;
    color: var(--rice-paper);
    font-size: 2rem;
    cursor: pointer;
    font-family: var(--font-display);
    transition: color 300ms ease;
}

.toc-close-btn:hover {
    color: var(--gold-leaf);
}

.toc-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.toc-item {
    display: flex;
    align-items: baseline;
    gap: 1rem;
    text-decoration: none;
    color: var(--rice-paper);
    transition: color 300ms ease;
}

.toc-item:hover {
    color: var(--gold-leaf);
}

.toc-item:hover .toc-title {
    background-size: 100% 1px;
}

.toc-numeral {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: clamp(1rem, 2vw, 1.4rem);
    color: var(--gold-leaf);
    width: 3rem;
    text-align: right;
    flex-shrink: 0;
}

.toc-title {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: clamp(1.4rem, 3vw, 2.2rem);
    line-height: 1.3;
    background-image: linear-gradient(var(--gold-leaf), var(--gold-leaf));
    background-size: 0% 1px;
    background-repeat: no-repeat;
    background-position: left bottom;
    transition: background-size 400ms ease;
    padding-bottom: 0.15em;
}

/* --- Spreads (General) --- */
.spread {
    position: relative;
    min-height: 100vh;
    width: 100%;
    overflow: hidden;
}

.spread-dark {
    background: var(--darkroom-black);
    color: var(--rice-paper);
}

.spread-light {
    background: var(--vellum-white);
    color: var(--sumi-ink);
}

/* --- Entry Screen --- */
#entry-screen {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
}

.entry-content {
    text-align: center;
}

.entry-title {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: clamp(3rem, 8vw, 6.5rem);
    color: var(--rice-paper);
    letter-spacing: 0.15em;
    line-height: 1.15;
}

.entry-title .letter {
    display: inline-block;
    opacity: 0;
    transform: translateY(8px);
}

.entry-title .letter.revealed {
    opacity: 1;
    transform: translateY(0);
    transition: opacity 350ms ease-out, transform 350ms ease-out;
}

.entry-line {
    width: 20%;
    height: 1px;
    background: var(--gold-leaf);
    margin: 1.5rem auto;
    transform: scaleX(0);
    transform-origin: center;
    transition: transform 600ms cubic-bezier(0.22, 1, 0.36, 1);
}

.entry-line.expanded {
    transform: scaleX(1);
}

.entry-subtitle {
    font-family: var(--font-body);
    font-style: italic;
    font-size: clamp(0.9rem, 1.5vw, 1.1rem);
    color: var(--temple-grey);
    opacity: 0;
    transition: opacity 500ms ease;
}

.entry-subtitle.visible {
    opacity: 1;
}

/* --- Folio Numbers --- */
.folio-number {
    position: absolute;
    top: 1.5rem;
    font-family: var(--font-ui);
    font-weight: 500;
    font-size: 0.75rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    z-index: 10;
}

.folio-recto {
    right: clamp(1.5rem, 4vw, 3rem);
    color: var(--gold-leaf);
}

.folio-verso {
    left: clamp(1.5rem, 4vw, 3rem);
}

.spread-dark .folio-verso {
    color: var(--gold-leaf);
}

.spread-light .folio-verso {
    color: var(--ash);
}

.spread-light .folio-recto {
    color: var(--ash);
}

/* --- Spread Grid --- */
.spread-grid {
    display: grid;
    grid-template-columns: 1fr 4fr 0.5fr 4fr 1fr;
    grid-template-rows: 1fr;
    min-height: 100vh;
    align-items: center;
    padding: clamp(4rem, 10vh, 8rem) 0;
}

/* --- Section Numbers --- */
.section-number {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: clamp(1rem, 2vw, 1.4rem);
    color: var(--gold-leaf);
    letter-spacing: 0.04em;
    display: block;
    margin-bottom: var(--baseline);
    opacity: 0;
    transition: opacity 300ms ease-out;
}

.section-number-light {
    color: var(--gold-leaf);
}

.in-view .section-number {
    opacity: 1;
}

/* --- Spread Headings --- */
.spread-heading {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: clamp(1.6rem, 3.5vw, 2.6rem);
    letter-spacing: 0.02em;
    line-height: 1.15;
    margin-bottom: var(--baseline);
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 500ms cubic-bezier(0.22, 1, 0.36, 1), transform 500ms cubic-bezier(0.22, 1, 0.36, 1);
}

.spread-heading-light {
    color: var(--sumi-ink);
}

.in-view .spread-heading {
    opacity: 1;
    transform: translateY(0);
}

/* --- Spread Body Text --- */
.spread-body {
    font-family: var(--font-body);
    font-weight: 400;
    font-size: clamp(1rem, 1.8vw, 1.15rem);
    line-height: 1.75;
    letter-spacing: 0.01em;
    margin-bottom: var(--baseline);
    opacity: 0;
    transform: translateY(15px);
    transition: opacity 400ms ease, transform 400ms ease;
}

.in-view .spread-body {
    opacity: 1;
    transform: translateY(0);
}

/* --- Drop Caps --- */
.drop-cap {
    float: left;
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 4.5em;
    line-height: 0.8;
    margin: 0 0.8rem 0.3rem 0;
    color: var(--gold-leaf);
}

.drop-cap-dark {
    float: left;
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 4.5em;
    line-height: 0.8;
    margin: 0 0.8rem 0.3rem 0;
    color: var(--rice-paper);
}

/* --- Section Divider (Decorative HR) --- */
.section-divider {
    border: none;
    width: 30%;
    margin: 0 auto;
    position: relative;
    height: 1px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.section-divider::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 0;
    width: 45%;
    height: 1px;
    background: var(--ash);
    transform: translateY(-50%);
}

.section-divider::after {
    content: '◆';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 0.6rem;
    color: var(--gold-leaf);
    background: var(--darkroom-black);
    padding: 0 0.5rem;
    z-index: 1;
}

.section-divider-light::after {
    background: var(--vellum-white);
}

.section-divider + .section-divider-line,
.section-divider::before + .section-divider::after {
    /* handled by pseudo elements */
}

/* The right line - using a wrapper approach with box-shadow */
.section-divider {
    background: transparent;
    overflow: visible;
}

/* Re-do section divider with outline trick */
.section-divider::before {
    width: calc(50% - 0.8rem);
    left: 0;
}

hr.section-divider {
    position: relative;
    border: none;
    height: 2rem;
    width: 30%;
    margin: 0 auto;
    background: transparent;
}

hr.section-divider::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 0;
    width: calc(50% - 1rem);
    height: 1px;
    background: var(--ash);
}

hr.section-divider::after {
    content: '◆';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 0.6rem;
    color: var(--gold-leaf);
    line-height: 1;
}

/* Right line via box-shadow trick on a span isn't viable in hr, use gradient approach */
hr.section-divider {
    background-image:
        linear-gradient(var(--ash), var(--ash));
    background-size: calc(50% - 1rem) 1px;
    background-position: right center;
    background-repeat: no-repeat;
}

hr.section-divider::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 0;
    width: calc(50% - 1rem);
    height: 1px;
    background: var(--ash);
}

/* --- Full-Bleed Image Spread --- */
.spread-fullbleed {
    position: relative;
}

.spread-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-size: cover;
    background-position: center;
    background-color: var(--darkroom-black);
    filter: saturate(0.8);
    mix-blend-mode: luminosity;
    will-change: transform;
}

.spread-fullbleed .spread-grid {
    position: relative;
    z-index: 2;
}

.fullbleed-panel {
    grid-column: 2 / 3;
    background: var(--night-overlay);
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
    padding: clamp(2rem, 4vw, 3rem);
    max-width: 520px;
}

/* --- Text-Heavy Spread --- */
.spread-text .spread-grid {
    align-items: center;
}

.spread-text .spread-left-page {
    grid-column: 2 / 3;
    padding-right: 2rem;
}

.spread-text .spread-gutter {
    grid-column: 3 / 4;
    width: 1px;
    height: 60%;
    background: var(--oxidized-copper);
    justify-self: center;
    align-self: center;
}

.spread-text .spread-right-page {
    grid-column: 4 / 5;
    padding-left: 2rem;
}

.pull-quote {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: clamp(1.8rem, 4vw, 3rem);
    line-height: 1.3;
    letter-spacing: 0.02em;
    font-style: italic;
    border: none;
    padding: 0;
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 500ms cubic-bezier(0.22, 1, 0.36, 1), transform 500ms cubic-bezier(0.22, 1, 0.36, 1);
}

.spread-light .pull-quote {
    color: var(--sumi-ink);
}

.in-view .pull-quote {
    opacity: 1;
    transform: translateY(0);
}

.text-columns {
    column-count: 2;
    column-gap: 2rem;
    column-rule: 1px solid var(--ash);
}

.text-columns p {
    font-family: var(--font-body);
    font-size: clamp(1rem, 1.8vw, 1.15rem);
    line-height: 1.75;
    margin-bottom: var(--baseline);
    opacity: 0;
    transform: translateY(15px);
    transition: opacity 400ms ease, transform 400ms ease;
}

.in-view .text-columns p {
    opacity: 1;
    transform: translateY(0);
}

/* --- Image-Text Spread --- */
.spread-imagetext .spread-left-page {
    grid-column: 2 / 3;
    padding-right: 1.5rem;
}

.spread-imagetext .spread-gutter {
    grid-column: 3 / 4;
    width: 1px;
    height: 60%;
    background: var(--oxidized-copper);
    justify-self: center;
    align-self: center;
}

.spread-imagetext .spread-right-text {
    grid-column: 4 / 5;
    padding-left: 2rem;
}

.spread-image-frame {
    position: relative;
    opacity: 0;
    transform: scale(1.03);
    transition: opacity 700ms ease-out, transform 700ms ease-out;
}

.in-view .spread-image-frame {
    opacity: 1;
    transform: scale(1);
}

.spread-image {
    width: 100%;
    aspect-ratio: 3 / 4;
    background-size: cover;
    background-position: center;
    background-color: var(--ash);
    filter: saturate(0.7) contrast(1.05);
    transition: filter 800ms ease, box-shadow 800ms ease;
    mix-blend-mode: luminosity;
}

.spread-dark .spread-image {
    mix-blend-mode: luminosity;
}

.spread-light .spread-image {
    mix-blend-mode: normal;
    border: 1px solid var(--ash);
    box-shadow: 4px 4px 0 var(--ash);
}

.spread-image:hover {
    filter: saturate(1.0) contrast(1.0);
    cursor: zoom-in;
}

.spread-light .spread-image:hover {
    box-shadow: 6px 6px 0 var(--ash);
}

.image-caption {
    display: block;
    text-align: right;
    font-family: var(--font-body);
    font-style: italic;
    font-size: clamp(0.8rem, 1.2vw, 0.9rem);
    color: var(--temple-grey);
    line-height: 1.5;
    margin-top: 0.75rem;
}

/* --- Folio Spread --- */
.spread-folio {
    padding: 0;
}

.folio-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 8vh;
    padding: 0 clamp(1.5rem, 4vw, 3rem);
    border-bottom: 1px solid var(--ash);
}

.running-header {
    font-family: var(--font-ui);
    font-weight: 500;
    font-size: clamp(0.7rem, 1vw, 0.85rem);
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--gold-leaf);
}

.folio-header .folio-number {
    position: static;
}

.folio-grid {
    display: grid;
    grid-template-columns: 2fr 5fr 3fr;
    gap: 2rem;
    padding: clamp(3rem, 6vh, 5rem) clamp(1.5rem, 4vw, 3rem);
    min-height: calc(100vh - 8vh);
    align-items: start;
}

/* Marginalia */
.folio-marginalia {
    position: sticky;
    top: 2rem;
    padding-right: 1.5rem;
    border-right: 1px solid var(--ash);
}

.marginalia-note {
    font-family: var(--font-body);
    font-style: italic;
    font-size: clamp(0.8rem, 1.2vw, 0.9rem);
    color: var(--temple-grey);
    line-height: 1.5;
    margin-bottom: 1.5rem;
    opacity: 0;
    transform: translateX(-20px);
    transition: opacity 400ms ease, transform 400ms ease;
    transition-delay: 200ms;
}

.in-view .marginalia-note {
    opacity: 1;
    transform: translateX(0);
}

/* Folio Main */
.folio-main {
    padding: 0 1rem;
}

.folio-main p {
    font-family: var(--font-body);
    font-size: clamp(1rem, 1.8vw, 1.15rem);
    line-height: 1.75;
    margin-bottom: var(--baseline);
    color: var(--sumi-ink);
    opacity: 0;
    transform: translateY(15px);
    transition: opacity 400ms ease, transform 400ms ease;
}

.in-view .folio-main p {
    opacity: 1;
    transform: translateY(0);
}

/* Sidebar */
.folio-sidebar {
    padding-left: 1.5rem;
    border-left: 1px solid var(--ash);
}

.sidebar-heading {
    font-family: var(--font-ui);
    font-weight: 500;
    font-size: clamp(0.7rem, 1vw, 0.85rem);
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--gold-leaf);
    margin-bottom: 1.5rem;
}

.sidebar-list {
    list-style: none;
    padding: 0;
}

.sidebar-list li {
    font-family: var(--font-body);
    font-size: clamp(0.85rem, 1.3vw, 0.95rem);
    line-height: 1.6;
    color: var(--sumi-ink);
    margin-bottom: 1rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--ash);
}

.sidebar-list li:last-child {
    border-bottom: none;
}

.sidebar-list li em {
    color: var(--temple-grey);
}

/* --- Footer --- */
#site-footer {
    min-height: 50vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.footer-content {
    max-width: 400px;
}

.footer-logo {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: clamp(1.6rem, 3vw, 2.4rem);
    letter-spacing: 0.15em;
    color: var(--rice-paper);
    display: block;
    margin-bottom: 1.5rem;
}

.footer-line {
    width: 60px;
    height: 1px;
    background: var(--gold-leaf);
    margin: 0 auto 1.5rem;
}

.footer-text {
    font-family: var(--font-body);
    font-style: italic;
    font-size: clamp(0.9rem, 1.5vw, 1.1rem);
    color: var(--temple-grey);
    margin-bottom: 1rem;
}

.footer-colophon {
    font-family: var(--font-ui);
    font-weight: 500;
    font-size: 0.7rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--ash);
}

/* --- Animations --- */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(15px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes settleIn {
    from {
        opacity: 0;
        transform: scale(1.03);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

@keyframes slideFromLeft {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* --- Stagger Delays (applied via JS or CSS) --- */
.in-view .spread-body:nth-child(2) { transition-delay: 100ms; }
.in-view .spread-body:nth-child(3) { transition-delay: 200ms; }
.in-view .spread-body:nth-child(4) { transition-delay: 300ms; }

.in-view .text-columns p:nth-child(1) { transition-delay: 0ms; }
.in-view .text-columns p:nth-child(2) { transition-delay: 100ms; }
.in-view .text-columns p:nth-child(3) { transition-delay: 200ms; }
.in-view .text-columns p:nth-child(4) { transition-delay: 300ms; }

.in-view .folio-main p:nth-child(1) { transition-delay: 0ms; }
.in-view .folio-main p:nth-child(2) { transition-delay: 100ms; }
.in-view .folio-main p:nth-child(3) { transition-delay: 200ms; }
.in-view .folio-main p:nth-child(4) { transition-delay: 300ms; }

.in-view .marginalia-note:nth-child(1) { transition-delay: 400ms; }
.in-view .marginalia-note:nth-child(2) { transition-delay: 500ms; }
.in-view .marginalia-note:nth-child(3) { transition-delay: 600ms; }
.in-view .marginalia-note:nth-child(4) { transition-delay: 700ms; }

/* Section number comes first */
.in-view .section-number { transition-delay: 0ms; }
/* Heading after section number */
.in-view .spread-heading { transition-delay: 200ms; }
/* Pull quote same timing as heading */
.in-view .pull-quote { transition-delay: 200ms; }
/* Spread body after heading */
.in-view .spread-body:nth-of-type(1) { transition-delay: 400ms; }
.in-view .spread-body:nth-of-type(2) { transition-delay: 500ms; }

/* Image settle */
.in-view .spread-image-frame { transition-delay: 100ms; }

/* --- Responsive --- */
@media (max-width: 900px) {
    .spread-grid {
        grid-template-columns: 1fr;
        padding: clamp(3rem, 6vh, 5rem) clamp(1.5rem, 6vw, 3rem);
        gap: 2rem;
    }

    .spread-text .spread-left-page,
    .spread-text .spread-right-page,
    .spread-imagetext .spread-left-page,
    .spread-imagetext .spread-right-text {
        grid-column: 1;
        padding: 0;
    }

    .spread-text .spread-gutter,
    .spread-imagetext .spread-gutter {
        display: none;
    }

    .fullbleed-panel {
        grid-column: 1;
        max-width: 100%;
    }

    .text-columns {
        column-count: 1;
    }

    .folio-grid {
        grid-template-columns: 1fr;
    }

    .folio-marginalia {
        position: static;
        border-right: none;
        border-bottom: 1px solid var(--ash);
        padding-right: 0;
        padding-bottom: 1.5rem;
        margin-bottom: 1.5rem;
    }

    .folio-sidebar {
        border-left: none;
        border-top: 1px solid var(--ash);
        padding-left: 0;
        padding-top: 1.5rem;
    }
}

@media (max-width: 600px) {
    .entry-title {
        letter-spacing: 0.08em;
    }

    .toc-title {
        font-size: clamp(1.1rem, 5vw, 1.6rem);
    }

    .pull-quote {
        font-size: clamp(1.4rem, 5vw, 2rem);
    }

    .drop-cap,
    .drop-cap-dark {
        font-size: 3.5em;
    }
}