/* =========================================================
   riron.net — 理論
   Bauhaus constructivism × scientific diagramming
   Swiss-inspired modular grid; manuscript-style margins
   ========================================================= */

:root {
    --paper: #fafafa;
    --theory-dark: #1a1a2e;
    --axiom-blue: #4361ee;
    --chalk-gray: #e8ecf1;
    --slate-indigo: #2a2a3e;
    --proof-purple: #7209b7;
    --frost-blue: #f0f4ff;
    --diagram-gray: #d4d9e3;
    --notation-color: #8b9cc2;

    --grid-step: 40px;
    --col-gutter: 20px;

    --font-display: "Space Grotesk", "Inter", system-ui, sans-serif;
    --font-body: "Literata", Georgia, "Times New Roman", serif;
    --font-mono: "Fira Code", ui-monospace, "SF Mono", Menlo, monospace;
    --font-label: "Inter", system-ui, sans-serif;

    --ease-quart: cubic-bezier(0.76, 0, 0.24, 1);
    --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
}

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

html {
    scroll-behavior: smooth;
}

html, body {
    margin: 0;
    padding: 0;
    background: var(--paper);
    color: var(--theory-dark);
    font-family: var(--font-body);
    font-size: 17px;
    line-height: 1.75;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

body {
    min-height: 100vh;
    position: relative;
}

::selection {
    background: var(--axiom-blue);
    color: var(--paper);
}

/* ---------- Graph-paper background ---------- */
.grid-bg {
    position: fixed;
    inset: 0;
    pointer-events: none;
    z-index: 0;
    background-image:
        linear-gradient(to right, var(--chalk-gray) 0.5px, transparent 0.5px),
        linear-gradient(to bottom, var(--chalk-gray) 0.5px, transparent 0.5px);
    background-size: var(--grid-step) var(--grid-step);
    background-position: 0 0;
    opacity: 0.55;
}

/* ---------- Connection-curve SVG layer ---------- */
.connection-layer {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 1;
    overflow: visible;
}

.connection-layer path {
    fill: none;
    stroke: var(--axiom-blue);
    stroke-opacity: 0.30;
    stroke-width: 1px;
    stroke-linecap: round;
    transition: stroke-opacity 320ms var(--ease-out), stroke-width 320ms var(--ease-out);
}

.connection-layer path.connection-revealed {
    animation: drawCurve 1100ms var(--ease-out) forwards;
}

.connection-layer path.connection-active {
    stroke-opacity: 0.95;
    stroke-width: 1.5px;
}

@keyframes drawCurve {
    from {
        stroke-dashoffset: var(--len, 1000);
    }
    to {
        stroke-dashoffset: 0;
    }
}

/* ---------- Opening / full-viewport narrative ---------- */
.opening {
    position: relative;
    min-height: 100vh;
    display: grid;
    grid-template-columns: minmax(80px, 1fr) minmax(320px, 720px) minmax(80px, 1fr);
    align-items: center;
    z-index: 2;
    padding: 40px 0 80px;
    border-bottom: 1px solid var(--slate-indigo);
}

.opening-margin {
    grid-column: 1 / 2;
    align-self: start;
    padding: 80px 0 0 40px;
    font-family: var(--font-display);
    font-size: 14px;
    font-weight: 500;
    color: var(--axiom-blue);
    letter-spacing: 0.04em;
}

.opening-num {
    display: inline-block;
    opacity: 0;
    transform: translateY(8px);
    transition: opacity 600ms var(--ease-out), transform 600ms var(--ease-out);
}

.opening-num.is-visible {
    opacity: 1;
    transform: translateY(0);
}

.opening-inner {
    grid-column: 2 / 3;
    text-align: left;
    position: relative;
}

.opening-prop {
    margin: 0;
    font-family: var(--font-body);
    font-size: clamp(22px, 2.4vw, 30px);
    font-weight: 400;
    line-height: 1.55;
    color: var(--theory-dark);
    letter-spacing: 0.005em;
}

.opening-prop .kanji {
    display: inline-block;
    margin-right: 12px;
    font-family: var(--font-display);
    font-weight: 500;
    color: var(--axiom-blue);
    letter-spacing: 0.02em;
    opacity: 0;
    transform: translateY(8px);
    transition: opacity 700ms var(--ease-out), transform 700ms var(--ease-out);
}

.opening-prop .em-dash {
    display: inline-block;
    margin-right: 10px;
    color: var(--slate-indigo);
    opacity: 0;
    transform: translateY(8px);
    transition: opacity 700ms var(--ease-out) 200ms, transform 700ms var(--ease-out) 200ms;
}

.opening-prop .word {
    display: inline-block;
    margin-right: 0.28em;
    opacity: 0;
    transform: translateY(8px);
    transition: opacity 600ms var(--ease-out), transform 600ms var(--ease-out);
}

.opening-prop.is-revealing .kanji,
.opening-prop.is-revealing .em-dash {
    opacity: 1;
    transform: translateY(0);
}

.opening-prop.is-revealing .word {
    opacity: 1;
    transform: translateY(0);
}

.opening-rule {
    display: block;
    margin-top: 36px;
    height: 1px;
    width: 0;
    background: var(--slate-indigo);
    transition: width 1500ms var(--ease-quart) 200ms;
}

.opening-rule.is-drawn {
    width: 100%;
}

.opening-meta {
    margin-top: 28px;
    font-family: var(--font-label);
    font-size: 12px;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.18em;
    color: var(--slate-indigo);
    opacity: 0;
    transition: opacity 600ms var(--ease-out) 1700ms;
}

.opening-prop.is-revealing ~ .opening-meta,
.opening.is-complete .opening-meta {
    opacity: 0.7;
}

.opening-scroll-hint {
    grid-column: 2 / 3;
    align-self: end;
    display: flex;
    align-items: center;
    gap: 12px;
    font-family: var(--font-label);
    font-size: 11px;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.22em;
    color: var(--slate-indigo);
    opacity: 0;
    transition: opacity 600ms var(--ease-out) 2100ms;
    padding-bottom: 40px;
}

.opening.is-complete .opening-scroll-hint {
    opacity: 0.6;
}

.opening-arrow {
    font-family: var(--font-display);
    animation: hintBob 2.4s ease-in-out infinite;
}

@keyframes hintBob {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(4px); }
}

/* ---------- Manuscript main layout ---------- */
.manuscript {
    position: relative;
    z-index: 2;
    max-width: 1440px;
    margin: 0 auto;
    padding: 120px 60px 160px;
    display: grid;
    grid-template-columns:
        [m-start] 60px
        [prop-start] minmax(0, 5fr)
        [prop-end gap-start] 30px
        [gap-end margin-start] minmax(0, 3fr)
        [margin-end] 60px [m-end];
    column-gap: 0;
    row-gap: 0;
}

.theorem-section {
    grid-column: m-start / m-end;
    display: grid;
    grid-template-columns: subgrid;
    margin-bottom: 120px;
    position: relative;
}

.section-header {
    grid-column: prop-start / margin-end;
    display: grid;
    grid-template-columns: 80px 1fr;
    align-items: baseline;
    column-gap: 24px;
    padding-bottom: 28px;
    margin-bottom: 56px;
    border-bottom: 1px solid var(--slate-indigo);
}

.section-num {
    font-family: var(--font-display);
    font-size: 42px;
    font-weight: 500;
    color: var(--axiom-blue);
    letter-spacing: 0.04em;
    line-height: 1;
}

.section-title {
    margin: 0 0 8px;
    font-family: var(--font-display);
    font-size: clamp(34px, 4vw, 52px);
    font-weight: 500;
    color: var(--theory-dark);
    letter-spacing: -0.01em;
    line-height: 1.05;
}

.section-blurb {
    grid-column: 2 / 3;
    margin: 0;
    font-family: var(--font-body);
    font-size: 17px;
    line-height: 1.65;
    color: var(--slate-indigo);
    max-width: 56ch;
}

/* ---------- Theorem blocks ---------- */
.theorem-block {
    grid-column: m-start / m-end;
    display: grid;
    grid-template-columns: subgrid;
    position: relative;
    padding: 28px 0 36px;
    margin-bottom: 8px;
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 400ms var(--ease-out), transform 400ms var(--ease-out);
}

.theorem-block.is-visible {
    opacity: 1;
    transform: translateY(0);
}

.theorem-block.is-pinged .prop-col {
    background: var(--frost-blue);
    transition: background 320ms var(--ease-out);
}

.prop-col {
    grid-column: prop-start / prop-end;
    position: relative;
    padding: 12px 28px 12px 32px;
    border: 1px solid var(--slate-indigo);
    background: var(--paper);
    transition: background 320ms var(--ease-out);
}

.prop-col::before {
    content: "";
    position: absolute;
    top: -1px;
    left: -1px;
    width: 14px;
    height: 14px;
    border-top: 2px solid var(--axiom-blue);
    border-left: 2px solid var(--axiom-blue);
    pointer-events: none;
}

.theorem-num {
    position: absolute;
    top: 18px;
    left: -64px;
    font-family: var(--font-display);
    font-size: 14px;
    font-weight: 500;
    color: var(--axiom-blue);
    letter-spacing: 0.04em;
    white-space: nowrap;
}

.theorem-title {
    margin: 4px 0 16px;
    font-family: var(--font-display);
    font-size: clamp(22px, 2.2vw, 32px);
    font-weight: 500;
    color: var(--theory-dark);
    letter-spacing: -0.005em;
    line-height: 1.18;
}

.prop-col p {
    margin: 0 0 16px;
    font-family: var(--font-body);
    font-size: 17px;
    line-height: 1.75;
    color: var(--theory-dark);
}

.prop-col p:last-child {
    margin-bottom: 0;
}

.prop-col em {
    font-style: italic;
    color: var(--slate-indigo);
}

/* ---------- Cross-reference links ---------- */
.xref {
    display: inline-block;
    padding: 0 4px;
    font-family: var(--font-display);
    font-size: 0.92em;
    font-weight: 500;
    color: var(--axiom-blue);
    text-decoration: none;
    border-bottom: 1px dashed currentColor;
    transition: color 260ms var(--ease-out), border-color 260ms var(--ease-out), background 260ms var(--ease-out);
    cursor: pointer;
}

.xref:hover {
    color: var(--proof-purple);
    border-bottom-style: solid;
    background: var(--frost-blue);
}

.xref:active {
    color: var(--proof-purple);
}

/* ---------- Inline & block code ---------- */
.inline-code {
    display: inline-block;
    padding: 1px 6px;
    margin: 0 1px;
    font-family: var(--font-mono);
    font-size: 0.88em;
    color: var(--notation-color);
    background: var(--frost-blue);
    border-radius: 2px;
}

.code-block {
    margin: 18px 0;
    padding: 16px 20px;
    font-family: var(--font-mono);
    font-size: 15px;
    line-height: 1.7;
    color: var(--theory-dark);
    background: var(--frost-blue);
    border-left: 3px solid var(--axiom-blue);
    overflow-x: auto;
    white-space: pre;
}

.code-block code {
    font-family: inherit;
    font-size: inherit;
    color: inherit;
    white-space: pre;
}

.code-block .k { color: var(--axiom-blue); font-weight: 500; }
.code-block .v { color: var(--proof-purple); }
.code-block .i { color: var(--theory-dark); }
.code-block .c { color: var(--notation-color); font-style: italic; }

/* ---------- QED tombstones ---------- */
.qed {
    display: inline-block;
    width: 8px;
    height: 8px;
    margin-left: 8px;
    background: var(--axiom-blue);
    transform: scale(0);
    transition: transform 200ms var(--ease-out);
    vertical-align: 0.05em;
}

.qed.is-set {
    transform: scale(1);
}

/* ---------- Margin column ---------- */
.margin-col {
    grid-column: margin-start / margin-end;
    display: flex;
    flex-direction: column;
    gap: 24px;
    padding-top: 8px;
    will-change: transform;
}

.margin-note {
    background: var(--chalk-gray);
    padding: 14px 16px 16px;
    border-left: 2px solid var(--slate-indigo);
    font-family: var(--font-label);
    font-size: 13px;
    line-height: 1.6;
    color: var(--slate-indigo);
}

.margin-note p {
    margin: 6px 0 0;
    font-family: var(--font-label);
    font-size: 13px;
    line-height: 1.65;
    color: var(--theory-dark);
}

.margin-note em {
    font-style: italic;
    color: var(--proof-purple);
}

.margin-tag {
    display: inline-block;
    font-family: var(--font-display);
    font-size: 10px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.18em;
    color: var(--axiom-blue);
}

.margin-figure {
    margin: 0;
    padding: 12px 14px 14px;
    background: var(--paper);
    border: 1px solid var(--diagram-gray);
}

.margin-figure .diagram {
    display: block;
    width: 100%;
    height: auto;
}

.margin-figure figcaption {
    margin-top: 8px;
    font-family: var(--font-label);
    font-size: 11.5px;
    line-height: 1.5;
    color: var(--slate-indigo);
    letter-spacing: 0.01em;
}

.diagram-label {
    font-family: var(--font-label);
    font-size: 11px;
    font-weight: 500;
    fill: var(--slate-indigo);
    text-anchor: middle;
}

.sketch {
    display: block;
    width: 100%;
    height: auto;
    margin-top: 10px;
}

.sketch-label {
    font-family: var(--font-display);
    font-size: 12px;
    fill: var(--proof-purple);
    fill-opacity: 0.6;
}

/* ---------- Section dividers ---------- */
.section-divider {
    grid-column: prop-start / margin-end;
    display: flex;
    align-items: center;
    margin: 24px 0 12px;
    height: 12px;
}

.divider-line {
    flex: 0 0 60%;
    height: 1px;
    background: var(--slate-indigo);
    opacity: 0.4;
}

.divider-node {
    display: inline-block;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    margin-left: -3px;
    background: var(--axiom-blue);
}

/* ---------- Persistent index nav ---------- */
.theorem-index {
    position: fixed;
    top: 50%;
    left: 24px;
    transform: translateY(-50%);
    z-index: 5;
    pointer-events: auto;
    font-family: var(--font-label);
    font-size: 11px;
    color: var(--slate-indigo);
    letter-spacing: 0.04em;
    max-height: 60vh;
    overflow: hidden;
    padding: 10px 12px 10px 0;
    border-left: 1px solid var(--diagram-gray);
    opacity: 0;
    transform: translate(-12px, -50%);
    transition: opacity 600ms var(--ease-out), transform 600ms var(--ease-out);
}

.theorem-index.is-shown {
    opacity: 0.85;
    transform: translate(0, -50%);
}

.index-label {
    display: block;
    margin: 0 0 8px 14px;
    font-family: var(--font-display);
    font-size: 10px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.22em;
    color: var(--axiom-blue);
}

.theorem-index ol {
    list-style: none;
    margin: 0;
    padding: 0;
}

.theorem-index li {
    margin: 0;
    padding: 3px 0 3px 14px;
    position: relative;
    cursor: pointer;
    transition: color 260ms var(--ease-out);
}

.theorem-index li::before {
    content: "";
    position: absolute;
    left: 0;
    top: 50%;
    width: 6px;
    height: 1px;
    background: var(--diagram-gray);
    transition: width 260ms var(--ease-out), background 260ms var(--ease-out);
}

.theorem-index li:hover {
    color: var(--proof-purple);
}

.theorem-index li:hover::before {
    width: 10px;
    background: var(--proof-purple);
}

.theorem-index li.is-current {
    color: var(--axiom-blue);
}

.theorem-index li.is-current::before {
    width: 10px;
    background: var(--axiom-blue);
}

/* ---------- Colophon ---------- */
.colophon {
    grid-column: prop-start / margin-end;
    margin-top: 80px;
    padding-top: 28px;
    border-top: 1px solid var(--slate-indigo);
    font-family: var(--font-label);
    font-size: 12px;
    color: var(--slate-indigo);
}

.colophon-line {
    display: flex;
    align-items: center;
    gap: 14px;
    font-family: var(--font-display);
    font-size: 12px;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.2em;
    color: var(--axiom-blue);
}

.colophon-dot {
    width: 4px;
    height: 4px;
    border-radius: 50%;
    background: var(--slate-indigo);
    opacity: 0.5;
}

.colophon-meta {
    margin: 12px 0 0;
    font-family: var(--font-body);
    font-size: 14px;
    line-height: 1.65;
    color: var(--slate-indigo);
}

/* ---------- Responsive collapse ---------- */
@media (max-width: 1200px) {
    .manuscript {
        grid-template-columns:
            [m-start] 40px
            [prop-start] minmax(0, 5fr)
            [prop-end gap-start] 24px
            [gap-end margin-start] minmax(0, 3fr)
            [margin-end] 40px [m-end];
        padding: 80px 36px 120px;
    }

    .theorem-index {
        display: none;
    }
}

@media (max-width: 900px) {
    .opening {
        grid-template-columns: 24px 1fr 24px;
        padding: 32px 0 60px;
    }

    .opening-margin {
        padding: 36px 0 0 24px;
    }

    .opening-prop {
        font-size: 22px;
    }

    .manuscript {
        grid-template-columns:
            [m-start] 56px
            [prop-start margin-start] 1fr
            [prop-end margin-end] 16px [m-end];
        padding: 60px 24px 80px;
    }

    .theorem-block {
        grid-template-columns: subgrid;
        padding: 20px 0 28px;
    }

    .prop-col {
        grid-column: prop-start / m-end;
        padding: 16px 20px;
    }

    .theorem-num {
        left: -56px;
        top: 20px;
    }

    .margin-col {
        grid-column: prop-start / m-end;
        padding-top: 16px;
        transform: none !important;
    }

    .section-header {
        grid-column: prop-start / m-end;
        grid-template-columns: 56px 1fr;
        column-gap: 16px;
    }

    .section-num {
        font-size: 32px;
    }

    .colophon {
        grid-column: prop-start / m-end;
    }

    .connection-layer {
        display: none;
    }
}

@media (max-width: 560px) {
    body {
        font-size: 16px;
    }

    .opening-prop {
        font-size: 20px;
    }

    .theorem-num {
        position: relative;
        top: auto;
        left: auto;
        display: inline-block;
        margin-bottom: 6px;
    }

    .prop-col {
        padding-left: 16px;
    }
}

/* ---------- Reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        transition-duration: 0.001ms !important;
        animation-duration: 0.001ms !important;
        animation-iteration-count: 1 !important;
    }

    .opening-prop .word,
    .opening-prop .kanji,
    .opening-prop .em-dash {
        opacity: 1;
        transform: none;
    }

    .opening-rule {
        width: 100%;
    }

    .theorem-block {
        opacity: 1;
        transform: none;
    }

    .qed {
        transform: scale(1);
    }
}