:root {
    --paper: #f6f3ec;
    --paper-strong: #fffdf8;
    --ink: #17212f;
    --muted: #627084;
    --line: #d8d2c4;
    --line-strong: #b8c1ce;
    --teal: #0f766e;
    --teal-dark: #115e59;
    --blue: #2563eb;
    --gold: #c47a1d;
    --rose: #be3455;
    --green: #168a4a;
    --shadow: 0 18px 55px rgba(23, 33, 47, 0.12);
    --radius: 8px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    min-height: 100vh;
    color: var(--ink);
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    line-height: 1.55;
    background:
        linear-gradient(90deg, rgba(23, 33, 47, 0.035) 1px, transparent 1px),
        linear-gradient(0deg, rgba(23, 33, 47, 0.03) 1px, transparent 1px),
        var(--paper);
    background-size: 44px 44px;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    -webkit-tap-highlight-color: transparent;
}

button,
select,
a {
    font: inherit;
}

button,
select {
    min-height: 44px;
}

button {
    cursor: pointer;
}

a {
    color: inherit;
}

#confetti-canvas {
    position: fixed;
    inset: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 20;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 10;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 18px;
    width: min(1180px, calc(100% - 32px));
    margin: 0 auto;
    padding: 14px 0;
    backdrop-filter: blur(18px);
}

.brand-mark {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
    color: var(--ink);
}

.brand-icon {
    display: grid;
    width: 42px;
    height: 42px;
    place-items: center;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    color: var(--paper-strong);
    background: var(--ink);
    font-weight: 800;
}

.brand-mark strong,
.brand-mark small {
    display: block;
    letter-spacing: 0;
}

.brand-mark strong {
    font-size: 0.98rem;
}

.brand-mark small {
    color: var(--muted);
    font-size: 0.78rem;
}

.language-toggle {
    display: inline-flex;
    gap: 4px;
    padding: 4px;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    background: rgba(255, 253, 248, 0.86);
    box-shadow: 0 8px 24px rgba(23, 33, 47, 0.08);
}

.language-toggle button {
    min-height: 36px;
    border: 0;
    border-radius: 6px;
    padding: 0 14px;
    color: var(--muted);
    background: transparent;
    font-size: 0.9rem;
    font-weight: 700;
}

.language-toggle button.active {
    color: var(--paper-strong);
    background: var(--teal);
}

main,
footer {
    width: min(1180px, calc(100% - 32px));
    margin: 0 auto;
}

.hero-section {
    display: grid;
    grid-template-columns: minmax(0, 1.35fr) minmax(320px, 0.65fr);
    gap: 28px;
    align-items: center;
    padding: clamp(38px, 8vh, 86px) 0 34px;
}

.hero-copy {
    position: relative;
}

.eyebrow {
    margin-bottom: 12px;
    color: var(--teal-dark);
    font-size: 0.78rem;
    font-weight: 800;
    letter-spacing: 0.13em;
    text-transform: uppercase;
}

h1,
h2,
h3 {
    letter-spacing: 0;
    line-height: 1.04;
}

h1 {
    max-width: 860px;
    font-size: clamp(3rem, 6.2vw, 5.75rem);
    font-weight: 900;
    overflow-wrap: break-word;
}

h1 span {
    display: block;
}

.hero-text {
    max-width: 680px;
    margin-top: 20px;
    color: var(--muted);
    font-size: clamp(1.12rem, 2vw, 1.38rem);
}

.author-credit {
    max-width: 760px;
    margin-top: 16px;
    color: var(--muted);
    font-size: 0.96rem;
}

.author-credit a {
    color: var(--teal-dark);
    font-weight: 800;
    text-decoration-color: rgba(15, 118, 110, 0.35);
    text-decoration-thickness: 2px;
    text-underline-offset: 3px;
}

.hero-actions,
.quiz-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    align-items: center;
    margin-top: 28px;
}

.primary-action,
.secondary-action,
.icon-action {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 46px;
    border-radius: var(--radius);
    border: 1px solid transparent;
    font-weight: 800;
    text-decoration: none;
    transition: transform 180ms ease, box-shadow 180ms ease, border-color 180ms ease, background 180ms ease;
}

.primary-action {
    padding: 0 20px;
    color: var(--paper-strong);
    background: var(--teal);
    box-shadow: 0 12px 28px rgba(15, 118, 110, 0.24);
}

.secondary-action {
    padding: 0 18px;
    color: var(--ink);
    background: var(--paper-strong);
    border-color: var(--line);
}

.icon-action {
    width: 46px;
    padding: 0;
    color: var(--ink);
    background: var(--paper-strong);
    border-color: var(--line);
}

.primary-action:hover,
.secondary-action:hover,
.icon-action:hover,
.carousel-btn:hover,
.option-btn:hover {
    transform: translateY(-2px);
}

.primary-action:focus-visible,
.secondary-action:focus-visible,
.icon-action:focus-visible,
.carousel-btn:focus-visible,
.dot:focus-visible,
.option-btn:focus-visible,
select:focus-visible,
.language-toggle button:focus-visible {
    outline: 3px solid rgba(37, 99, 235, 0.24);
    outline-offset: 2px;
}

.event-panel {
    padding: 24px;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    background: rgba(255, 253, 248, 0.94);
    box-shadow: var(--shadow);
}

.status-row {
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--muted);
    font-size: 0.9rem;
    font-weight: 800;
}

.status-dot {
    width: 10px;
    height: 10px;
    border-radius: 999px;
    background: var(--green);
    box-shadow: 0 0 0 6px rgba(22, 138, 74, 0.12);
}

.event-date {
    display: block;
    margin: 18px 0 8px;
    font-size: clamp(2rem, 4vw, 3.2rem);
    line-height: 1;
}

.event-panel p {
    color: var(--muted);
}

.countdown-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
    margin-top: 22px;
}

.countdown-grid div {
    min-width: 0;
    padding: 14px 8px;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    text-align: center;
    background: #f9f7f1;
}

.countdown-grid span {
    display: block;
    color: var(--blue);
    font-size: clamp(1.7rem, 4vw, 2.4rem);
    font-weight: 900;
    line-height: 1;
}

.countdown-grid small {
    display: block;
    margin-top: 6px;
    color: var(--muted);
    font-size: 0.78rem;
    font-weight: 800;
}

.metrics-grid,
.principles-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 14px;
}

.metric-card,
.principle-card,
.fact-card,
.quiz-container,
.simulator-layout,
.portrait-panel,
.timeline-item,
.ledger-column {
    border: 1px solid var(--line);
    border-radius: var(--radius);
    background: rgba(255, 253, 248, 0.94);
    box-shadow: 0 10px 30px rgba(23, 33, 47, 0.07);
}

.metric-card {
    padding: 20px;
}

.metric-card > span,
.metric-card small {
    display: block;
    color: var(--muted);
}

.metric-card > span {
    font-size: 0.82rem;
    font-weight: 800;
    text-transform: uppercase;
}

.metric-card strong {
    display: block;
    margin: 8px 0 6px;
    color: var(--ink);
    font-size: clamp(2rem, 4vw, 3.4rem);
    line-height: 1;
}

.metric-card strong span {
    display: inline;
}

.metric-card small {
    font-size: 0.9rem;
}

section {
    padding: 70px 0;
}

.section-heading {
    max-width: 760px;
    margin-bottom: 24px;
}

.section-heading h2 {
    font-size: clamp(2rem, 4vw, 3.4rem);
    font-weight: 900;
}

.pacioli-layout {
    display: grid;
    grid-template-columns: 360px minmax(0, 1fr);
    gap: 22px;
    align-items: stretch;
}

.portrait-panel {
    overflow: hidden;
    min-height: 100%;
}

.portrait-image {
    display: block;
    width: 100%;
    aspect-ratio: 1 / 1;
    object-fit: cover;
    background: #e8e0d1;
}

.portrait-panel figcaption {
    padding: 16px;
    color: var(--muted);
    font-size: 0.95rem;
}

.fact-list {
    display: grid;
    gap: 12px;
}

.fact-item {
    display: grid;
    grid-template-columns: 70px minmax(0, 1fr);
    gap: 16px;
    align-items: start;
    padding: 18px;
    border-left: 4px solid var(--gold);
    border-radius: var(--radius);
    background: rgba(255, 253, 248, 0.8);
}

.fact-icon {
    display: grid;
    min-height: 42px;
    place-items: center;
    border-radius: var(--radius);
    color: var(--paper-strong);
    background: var(--ink);
    font-size: 0.92rem;
    font-weight: 900;
}

.fact-item strong {
    display: block;
    margin-bottom: 5px;
    font-size: 1.1rem;
}

.fact-item p,
.principle-card p,
.timeline-item p,
.transaction-explanation {
    color: var(--muted);
}

.simulator-layout {
    display: grid;
    grid-template-columns: minmax(280px, 0.92fr) minmax(0, 1.08fr);
    gap: 18px;
    padding: 18px;
}

.transaction-picker {
    display: flex;
    flex-direction: column;
    gap: 14px;
}

.transaction-picker label {
    color: var(--muted);
    font-size: 0.82rem;
    font-weight: 900;
    text-transform: uppercase;
}

select {
    width: 100%;
    border: 1px solid var(--line-strong);
    border-radius: var(--radius);
    padding: 0 14px;
    color: var(--ink);
    background: var(--paper-strong);
    font-weight: 700;
}

.equation-strip {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    align-items: center;
    padding: 14px;
    border: 1px dashed var(--line-strong);
    border-radius: var(--radius);
    background: #f8f2e8;
}

.equation-strip span {
    padding: 6px 9px;
    border-radius: 6px;
    color: var(--ink);
    background: var(--paper-strong);
    font-size: 0.92rem;
    font-weight: 800;
}

.ledger-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px;
}

.ledger-column {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    min-height: 220px;
    padding: 20px;
}

.ledger-column h3 {
    font-size: 1rem;
    text-transform: uppercase;
}

.ledger-column p {
    margin: 22px 0;
    color: var(--muted);
    font-size: clamp(1.4rem, 3vw, 2.1rem);
    font-weight: 900;
    line-height: 1.1;
}

.ledger-column strong {
    color: var(--paper-strong);
    align-self: flex-start;
    border-radius: 999px;
    padding: 7px 12px;
    background: var(--ink);
}

.ledger-column.debit {
    border-top: 5px solid var(--blue);
}

.ledger-column.credit {
    border-top: 5px solid var(--rose);
}

.timeline {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 12px;
}

.timeline-item {
    padding: 18px;
}

.timeline-item span {
    display: inline-flex;
    margin-bottom: 18px;
    color: var(--gold);
    font-size: 0.88rem;
    font-weight: 900;
}

.timeline-item strong {
    display: block;
    margin-bottom: 8px;
    font-size: 1.1rem;
}

.facts-carousel {
    display: grid;
    grid-template-columns: 52px minmax(0, 1fr) 52px;
    gap: 14px;
    align-items: center;
}

.carousel-btn {
    width: 52px;
    height: 52px;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    color: var(--ink);
    background: var(--paper-strong);
    font-size: 1.25rem;
    font-weight: 900;
}

.fact-card {
    position: relative;
    min-height: 184px;
    padding: 32px;
}

.fact-number {
    display: block;
    margin-bottom: 16px;
    color: var(--gold);
    font-weight: 900;
}

.fact-text {
    max-width: 860px;
    color: var(--ink);
    font-size: clamp(1.2rem, 2vw, 1.65rem);
    font-weight: 800;
    line-height: 1.32;
}

.carousel-dots {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    justify-content: center;
    margin-top: 16px;
}

.dot {
    width: 12px;
    min-height: 12px;
    height: 12px;
    border: 0;
    border-radius: 999px;
    background: var(--line-strong);
}

.dot.active {
    width: 34px;
    background: var(--teal);
}

.quiz-container {
    padding: 24px;
}

.quiz-topline {
    display: flex;
    justify-content: space-between;
    gap: 18px;
    color: var(--muted);
    font-size: 0.86rem;
    font-weight: 900;
    text-transform: uppercase;
}

.progress-track {
    height: 9px;
    margin: 12px 0 24px;
    overflow: hidden;
    border-radius: 999px;
    background: #e7e0d4;
}

#quiz-progress-bar {
    width: 0;
    height: 100%;
    border-radius: inherit;
    background: var(--green);
    transition: width 240ms ease;
}

#question-text {
    margin-bottom: 18px;
    font-size: clamp(1.25rem, 2.2vw, 2rem);
}

.options {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px;
}

.option-btn {
    min-height: 72px;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: 14px;
    color: var(--ink);
    background: var(--paper-strong);
    text-align: left;
    font-weight: 800;
    transition: transform 180ms ease, border-color 180ms ease, background 180ms ease;
}

.option-btn:hover {
    border-color: var(--blue);
}

.option-btn.correct {
    color: #0f3f2a;
    border-color: rgba(22, 138, 74, 0.35);
    background: #dff2e8;
}

.option-btn.incorrect {
    color: #66192a;
    border-color: rgba(190, 52, 85, 0.35);
    background: #f8dde5;
}

.option-btn:disabled {
    cursor: default;
}

.quiz-result {
    min-height: 54px;
    margin-top: 16px;
    padding: 14px;
    border-radius: var(--radius);
    color: var(--muted);
    background: #f9f7f1;
}

.quiz-result:empty {
    visibility: hidden;
}

.quiz-result.correct {
    color: #0f3f2a;
    background: #dff2e8;
}

.quiz-result.incorrect {
    color: #66192a;
    background: #f8dde5;
}

.principles-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.principle-card {
    min-height: 196px;
    padding: 20px;
}

.principle-icon {
    display: inline-grid;
    width: 42px;
    height: 42px;
    place-items: center;
    margin-bottom: 30px;
    border-radius: var(--radius);
    color: var(--paper-strong);
    background: var(--blue);
    font-size: 0.86rem;
    font-weight: 900;
}

.principle-card h3 {
    margin-bottom: 8px;
    font-size: 1.18rem;
}

footer {
    padding: 34px 0 44px;
    color: var(--muted);
    border-top: 1px solid var(--line);
}

footer p + p {
    margin-top: 8px;
}

.footer-quote {
    color: var(--ink);
    font-weight: 800;
}

@media (max-width: 920px) {
    .hero-section,
    .pacioli-layout,
    .simulator-layout {
        grid-template-columns: 1fr;
    }

    .hero-section {
        min-height: auto;
        padding-top: 36px;
    }

    .metrics-grid,
    .timeline,
    .principles-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .portrait-panel {
        max-width: 420px;
    }
}

@media (max-width: 680px) {
    .site-header {
        position: relative;
        align-items: flex-start;
        flex-direction: column;
    }

    .language-toggle {
        width: 100%;
    }

    .language-toggle button {
        flex: 1;
    }

    main,
    footer,
    .site-header {
        width: min(100% - 24px, 1180px);
    }

    h1 {
        font-size: clamp(2.05rem, 9vw, 2.35rem);
        overflow-wrap: anywhere;
    }

    .author-credit,
    .author-credit a {
        overflow-wrap: anywhere;
    }

    section {
        padding: 48px 0;
    }

    .metrics-grid,
    .timeline,
    .principles-grid,
    .ledger-grid,
    .options {
        grid-template-columns: 1fr;
    }

    .event-panel,
    .quiz-container,
    .simulator-layout,
    .fact-card {
        padding: 18px;
    }

    .countdown-grid {
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }

    .countdown-grid div {
        padding: 12px 4px;
    }

    .facts-carousel {
        grid-template-columns: 1fr;
    }

    .carousel-btn {
        display: none;
    }

    .fact-item {
        grid-template-columns: 1fr;
    }

    .fact-icon {
        width: 70px;
    }
}

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        scroll-behavior: auto !important;
        transition-duration: 0.01ms !important;
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
    }
}

/* Premium finish: preserve the reference layout, hierarchy and learning sections. */
:root {
    --paper: #f7f5f0;
    --paper-strong: #fffefa;
    --ink: #1c302f;
    --muted: #667572;
    --line: #e2e3d9;
    --line-strong: #bdcbc4;
    --teal: #176b60;
    --teal-dark: #15594f;
    --blue: #276b94;
    --gold: #a57936;
    --radius: 16px;
    --shadow: 0 24px 64px -24px rgba(26, 55, 48, .2);
}
body {
    background: radial-gradient(ellipse at 85% 6%, #e1ede55e, transparent 35%),
        linear-gradient(90deg, #213f3205 1px, transparent 1px),
        linear-gradient(0deg, #213f3205 1px, transparent 1px), var(--paper);
    background-size: auto, 56px 56px, 56px 56px, auto;
}
html { scroll-padding-top: 104px; }
[hidden] { display: none !important; }
.skip-link { position: fixed; top: -100px; left: 20px; z-index: 40; padding: 16px; background: var(--paper-strong); }
.skip-link:focus { top: 12px; }
a:focus-visible, button:focus-visible, select:focus-visible { outline: 3px solid #a57936; outline-offset: 4px; }
.site-header { padding: 19px 0; background: #f7f5f0e8; border-bottom: 1px solid var(--line); }
.brand-icon { width: 46px; height: 46px; border-radius: 13px; background: linear-gradient(135deg, #205d50, #153f36); border: 1px solid #456e5e; color: #e9cf9c; font: 28px Georgia, serif; box-shadow: 0 6px 14px #153f3618; }
.brand-mark strong { font-size: .92rem; font-weight: 700; }
.brand-mark small { margin-top: 3px; font-size: .72rem; }
.language-toggle { box-shadow: none; border-radius: 11px; }
.language-toggle button { font-size: .8rem; font-weight: 600; border-radius: 7px; }
.hero-section { gap: 52px; padding: 76px 0 48px; grid-template-columns: minmax(0, 1.3fr) minmax(320px, .7fr); }
h1 { font-family: Georgia, 'Times New Roman', serif; font-weight: 400; font-size: clamp(2.8rem, 5.2vw, 4.5rem); letter-spacing: -.045em; line-height: 1.1; }
h1 span:last-child { color: var(--teal); }
.eyebrow { font-weight: 700; font-size: .69rem; letter-spacing: .16em; margin-bottom: 16px; }
#event-kicker { display: inline-flex; align-items: center; gap: 9px; padding: 7px 12px; border: 1px solid #d8e3d9; border-radius: 100px; background: #edf3e9; letter-spacing: .09em; }
#event-kicker::before { content: ''; width: 5px; height: 5px; border-radius: 50%; background: var(--teal); }
.hero-text { font-size: 1.08rem; line-height: 1.8; max-width: 560px; margin-top: 24px; }
.author-credit { font-size: .82rem; line-height: 1.8; margin-top: 18px; }
.author-credit span { display: block; }
.author-credit a { font-weight: 600; text-decoration-thickness: 1px; }
.primary-action, .secondary-action, .icon-action { border-radius: 10px; font-size: .86rem; font-weight: 650; min-height: 49px; }
.primary-action { box-shadow: 0 8px 20px #176b601a; padding: 0 24px; }
.primary-action:hover { background: var(--teal-dark); }
#start-learning::after { content: '↗'; margin-left: 25px; }
.icon-action { width: 49px; color: var(--gold); }
.event-panel { padding: 32px; position: relative; overflow: hidden; border-top: 3px solid #b49661; background: linear-gradient(145deg, #fffefb, #f2f4ec); box-shadow: var(--shadow); }
.event-panel::after { content: ''; width: 170px; height: 170px; border: 1px solid #a5793610; border-radius: 50%; position: absolute; top: -90px; right: -50px; pointer-events: none; }
.status-row { font-size: .72rem; letter-spacing: .04em; font-weight: 600; }
.status-dot { width: 6px; height: 6px; box-shadow: 0 0 0 4px #168a4a0c; }
.event-date { font-family: Georgia, serif; font-size: clamp(1.7rem, 2.7vw, 2.55rem); font-weight: 400; letter-spacing: -.04em; margin: 25px 0 12px; }
.event-panel p { font-size: .8rem; line-height: 1.7; min-height: 42px; }
.countdown-grid { gap: 8px; margin-top: 24px; }
.countdown-grid div { background: #fffefa; border-color: #e2e5db; border-radius: 10px; padding: 18px 6px; }
.countdown-grid span { color: var(--teal-dark); font-size: 2.05rem; font-weight: 500; font-variant-numeric: tabular-nums; }
.countdown-grid small { font-size: .67rem; font-weight: 500; margin-top: 8px; }
.metrics-grid { padding: 0 0 40px; gap: 18px; }
.metric-card { padding: 25px; box-shadow: none; background: #fffefabf; }
.metric-card > span { font-weight: 600; font-size: .66rem; letter-spacing: .08em; }
.metric-card strong { font-family: Georgia, serif; font-size: 2.6rem; font-weight: 400; margin: 15px 0 10px; }
.metric-card small { font-size: .76rem; }
section { padding: 53px 0; }
.section-heading { margin-bottom: 28px; }
.section-heading h2 { font-family: Georgia, serif; font-weight: 400; font-size: clamp(1.8rem, 3.2vw, 2.65rem); line-height: 1.18; letter-spacing: -.025em; }
.pacioli-section, .timeline-section, .quiz-section, .principles-section { border-top: 1px solid var(--line); }
.pacioli-layout { grid-template-columns: 300px minmax(0, 1fr); gap: 30px; }
.portrait-panel { box-shadow: none; }
.portrait-image { filter: saturate(.7); }
.portrait-panel figcaption { font-size: .76rem; text-align: center; padding: 20px; }
.fact-item { border: 1px solid var(--line); border-left: 3px solid #b8985d; padding: 21px; gap: 19px; background: #fffefaab; }
.fact-icon { background: #eaf0e8; color: var(--teal-dark); font-size: .83rem; font-weight: 600; border: 1px solid #dce6db; border-radius: 9px; }
.fact-item strong { font-weight: 650; font-size: .98rem; }
.fact-item p, .timeline-item p, .principle-card p { font-size: .86rem; line-height: 1.8; }
.simulator-layout { padding: 30px; gap: 30px; box-shadow: 0 16px 40px -25px #23463933; }
.transaction-picker { gap: 18px; }
.transaction-picker label { font-size: .69rem; letter-spacing: .06em; font-weight: 600; }
select { border-radius: 9px; font-size: .85rem; font-weight: 500; min-height: 50px; }
.equation-strip { background: #f4f4ec; padding: 12px; border-style: solid; border-color: #e1e4d6; gap: 6px; }
.equation-strip span { font-size: .76rem; font-weight: 600; padding: 6px; background: transparent; }
.transaction-explanation { font-size: .85rem; line-height: 1.85; }
.ledger-column { min-height: 225px; box-shadow: none; background: #f8faf6; }
.ledger-column h3 { font-size: .72rem; font-weight: 600; letter-spacing: .14em; }
.ledger-column p { font-family: Georgia, serif; font-size: 1.7rem; font-weight: 400; color: var(--ink); line-height: 1.25; }
.ledger-column strong { padding: 6px 12px; font-size: .9rem; font-weight: 500; background: #e5ede3; color: var(--teal-dark); }
.ledger-column.debit { border-top: 3px solid #4b8390; }
.ledger-column.credit { border-top: 3px solid #b1925b; }
.timeline { gap: 18px; }
.timeline-item { padding: 24px; box-shadow: none; }
.timeline-item span { font-size: .83rem; font-weight: 650; margin-bottom: 21px; }
.timeline-item strong { font-size: .94rem; font-weight: 600; line-height: 1.5; }
.fact-card { padding: 32px 40px; background: linear-gradient(115deg, #eef3e9, #fffefa); box-shadow: none; }
.fact-number { font-size: .76rem; letter-spacing: .16em; }
.fact-text { font-family: Georgia, serif; font-size: 1.55rem; font-weight: 400; line-height: 1.55; }
.carousel-btn { border-radius: 50%; font-weight: 400; }
.dot { min-height: 32px; width: 32px; background: radial-gradient(circle, var(--line-strong) 4px, transparent 5px); }
.dot.active { width: 32px; background: radial-gradient(circle, var(--teal) 5px, transparent 6px); }
.quiz-container { padding: 34px; box-shadow: none; }
.quiz-topline { font-size: .73rem; font-weight: 600; letter-spacing: .05em; }
.progress-track { height: 5px; background: #e9ede3; margin-bottom: 30px; }
#quiz-progress-bar { background: var(--teal); }
#question-text { font-size: clamp(1.1rem, 2vw, 1.6rem); font-weight: 600; line-height: 1.5; margin-bottom: 23px; }
.option-btn { font-size: .86rem; font-weight: 500; border-radius: 10px; min-height: 65px; padding: 18px; }
.option-btn:disabled:hover { transform: none; }
.quiz-result { font-size: .86rem; line-height: 1.7; }
.principles-grid { gap: 18px; }
.principle-card { box-shadow: none; padding: 26px; }
.principle-icon { border-radius: 50%; width: 35px; height: 35px; background: #edf0e4; color: #67754b; font-weight: 500; font-size: .75rem; margin-bottom: 23px; }
.principle-card h3 { font-size: .98rem; font-weight: 600; line-height: 1.5; }
footer { font-size: .82rem; padding: 30px 0 40px; }
.footer-quote { font-family: Georgia, serif; font-size: 1.15rem; font-weight: 400; }
.footer-year { font-size: .7rem; padding-top: 15px; }
@media (max-width: 920px) {
    .hero-section, .pacioli-layout { grid-template-columns: 1fr; }
    .hero-section { gap: 30px; padding-top: 45px; }
    .hero-copy { max-width: 690px; }
    .event-panel { max-width: 580px; width: 100%; }
    .event-date { font-size: 2.4rem; }
    .metrics-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
    .pacioli-layout { grid-template-columns: 240px minmax(0, 1fr); }
    .fact-item { grid-template-columns: 1fr; gap: 10px; }
    .fact-icon { width: 65px; }
}
@media (max-width: 680px) {
    main, footer, .site-header { width: calc(100% - 36px); }
    .site-header { flex-direction: row; align-items: center; gap: 10px; padding: 16px 0; }
    .brand-mark { gap: 8px; }
    .brand-icon { width: 34px; height: 38px; font-size: 23px; }
    .brand-mark strong { font-size: .69rem; }
    .brand-mark small { font-size: .59rem; }
    .language-toggle { width: auto; padding: 3px; gap: 0; }
    .language-toggle button { font-size: .65rem; padding: 0 8px; min-height: 35px; }
    h1 { font-size: clamp(2.1rem, 9vw, 3.5rem); letter-spacing: -.045em; overflow-wrap: normal; }
    .hero-section { padding-top: 35px; }
    #event-kicker { font-size: .57rem; letter-spacing: .04em; }
    .hero-text { font-size: .94rem; }
    .author-credit { font-size: .76rem; }
    .metrics-grid, .pacioli-layout { grid-template-columns: 1fr; }
    .metrics-grid { gap: 10px; padding-bottom: 25px; }
    .metric-card { display: grid; grid-template-columns: 1fr auto; gap: 7px 12px; padding: 18px 20px; align-items: center; }
    .metric-card > strong { grid-row: 1 / 3; grid-column: 2; margin: 0; font-size: 2rem; }
    .metric-card > span { font-size: .59rem; }
    .metric-card small { font-size: .7rem; }
    .event-panel, .quiz-container, .simulator-layout { padding: 23px; }
    .portrait-panel { width: 100%; max-width: 360px; }
    .ledger-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .ledger-column { padding: 15px; min-height: 190px; }
    .ledger-column p { font-size: 1.25rem; overflow-wrap: anywhere; }
    .ledger-column strong { font-size: .78rem; padding: 5px 9px; }
    .facts-carousel { grid-template-columns: 38px minmax(0, 1fr) 38px; gap: 7px; }
    .carousel-btn { display: block; width: 38px; height: 44px; }
    .fact-card { padding: 22px; min-height: 230px; }
    .fact-text { font-size: 1.1rem; }
    section { padding: 38px 0; }
    .section-heading h2 { font-size: 1.95rem; }
}

.back-to-top {
    position: fixed;
    right: max(20px, env(safe-area-inset-right));
    bottom: max(20px, env(safe-area-inset-bottom));
    z-index: 15;
    display: grid;
    place-items: center;
    width: 48px;
    height: 48px;
    border: 1px solid #176b6040;
    border-radius: 50%;
    background: #f7f5f035;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    color: var(--teal-dark);
    font-size: 24px;
    font-weight: 500;
    text-decoration: none;
    transition: background 180ms ease, transform 180ms ease;
}
.back-to-top:hover {
    background: #f7f5f0b3;
    transform: translateY(-3px);
}
footer { padding-bottom: 88px; }