/*  Materials Science from the Beginning — design system
    ----------------------------------------------------
    The Curionode editorial look, written for this course: warm paper,
    Fraunces for display, Source Serif for prose, JetBrains Mono for numbers.

    Figure colours are tokens with one meaning each: blue atoms and lattices,
    plum defects, teal liquids and diffusing species, ochre heat and the
    furnace, sienna stress and load, green a property met, red a crack or a
    limit, ink measurement. Canvases read them through js/figure.js as FIG.
    The dark values are written twice — for the system preference and for an
    explicit choice — and must stay identical.
*/
@import url('../vendor/fonts/fonts.css');

:root {
    --paper: #fbf8f3;  --paper-deep: #f3ecdf;  --paper-vellum: #efe7d7;  --paper-rule: #e2d8c4;
    --ink: #1b1b1f;  --ink-soft: #3a3a40;  --ink-mute: #6c6c73;  --ink-faint: #9a958b;
    --red: #b3302d;  --red-tint: #f5e6e2;  --blue: #1f4fc9;  --blue-tint: #e6ecf6;  --teal: #0f6d68;  --teal-tint: #e0eeeb;
    --plum: #5b3b7b;  --plum-tint: #ece2f0;  --ochre: #b6781a;  --ochre-tint: #f5e6c6;  --green: #2c6a4e;  --green-tint: #dfece3;
    --sienna: #a6520e;  --olive: #5b5b1d;  --input: #fffefa;
    --fig-paper: #fffdf7;  --fig-grid: #d2c9b3;  --fig-rule: #e2d8c4;  --fig-ink: #1b1b1f;  --fig-muted: #6c6c73;  --fig-faint: #a39e93;
    --fig-blue: #1f4fc9;  --fig-red: #b3302d;  --fig-green: #2c6a4e;  --fig-teal: #0f6d68;  --fig-plum: #6b3f94;  --fig-ochre: #c27f12;  --fig-sienna: #a6520e;  --fig-olive: #6a6a2a;
    --shadow: 0 2px 6px rgba(27, 27, 31, 0.06);  --shadow-lg: 0 10px 30px rgba(27, 27, 31, 0.14);
    --font-display: 'Fraunces', 'Iowan Old Style', Georgia, serif;
    --font-body: 'Source Serif 4', 'Iowan Old Style', Georgia, serif;
    --font-mono: 'JetBrains Mono', ui-monospace, Menlo, Consolas, monospace;
}
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
    --paper: #14130e;  --paper-deep: #1c1a13;  --paper-vellum: #211f16;  --paper-rule: #3a3529;
    --ink: #ece5d5;  --ink-soft: #c9c1ae;  --ink-mute: #9c9483;  --ink-faint: #766f60;
    --red: #e3716a;  --red-tint: #3b211e;  --blue: #84a9f4;  --blue-tint: #1d2740;  --teal: #52b6ae;  --teal-tint: #15302d;
    --plum: #b694d9;  --plum-tint: #2c2339;  --ochre: #e6b459;  --ochre-tint: #3b3016;  --green: #6dbb8f;  --green-tint: #1a3025;
    --sienna: #e48d48;  --olive: #b9b96b;  --input: #1b1912;
    --fig-paper: #17150f;  --fig-grid: #3b3528;  --fig-rule: #3b3528;  --fig-ink: #ece5d5;  --fig-muted: #9c9483;  --fig-faint: #776f60;
    --fig-blue: #84a9f4;  --fig-red: #e3716a;  --fig-green: #6dbb8f;  --fig-teal: #52b6ae;  --fig-plum: #b694d9;  --fig-ochre: #e6b459;  --fig-sienna: #e48d48;  --fig-olive: #b9b96b;
    --shadow: 0 2px 6px rgba(0, 0, 0, 0.38);  --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.5);
    }
}
:root[data-theme="dark"] {
    --paper: #14130e;  --paper-deep: #1c1a13;  --paper-vellum: #211f16;  --paper-rule: #3a3529;
    --ink: #ece5d5;  --ink-soft: #c9c1ae;  --ink-mute: #9c9483;  --ink-faint: #766f60;
    --red: #e3716a;  --red-tint: #3b211e;  --blue: #84a9f4;  --blue-tint: #1d2740;  --teal: #52b6ae;  --teal-tint: #15302d;
    --plum: #b694d9;  --plum-tint: #2c2339;  --ochre: #e6b459;  --ochre-tint: #3b3016;  --green: #6dbb8f;  --green-tint: #1a3025;
    --sienna: #e48d48;  --olive: #b9b96b;  --input: #1b1912;
    --fig-paper: #17150f;  --fig-grid: #3b3528;  --fig-rule: #3b3528;  --fig-ink: #ece5d5;  --fig-muted: #9c9483;  --fig-faint: #776f60;
    --fig-blue: #84a9f4;  --fig-red: #e3716a;  --fig-green: #6dbb8f;  --fig-teal: #52b6ae;  --fig-plum: #b694d9;  --fig-ochre: #e6b459;  --fig-sienna: #e48d48;  --fig-olive: #b9b96b;
    --shadow: 0 2px 6px rgba(0, 0, 0, 0.38);  --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.5);
}

/* ─── Base ─────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--paper); color: var(--ink); font: 17px/1.62 var(--font-body); font-optical-sizing: auto; }
::selection { background: var(--ochre-tint); }
a { color: var(--blue); text-underline-offset: 2px; }
code, kbd, .mono { font-family: var(--font-mono); font-size: 0.86em; }
p code, li code, dd code { background: var(--paper-deep); border: 1px solid var(--paper-rule); border-radius: 3px; padding: 0 0.28em; }
button { font: inherit; color: inherit; }
:focus-visible { outline: 2px solid var(--blue); outline-offset: 2px; }
sub, sup { line-height: 0; }
h1, h2, h3 { font-family: var(--font-display); font-weight: 400; letter-spacing: -0.01em; }
html[lang^="zh"] body { font-family: var(--font-body), 'Songti SC', 'Noto Serif CJK SC', 'Source Han Serif SC', serif; }
.btn { border: 1px solid var(--paper-rule); background: var(--paper); color: var(--ink); cursor: pointer; font: 13px var(--font-mono); padding: 6px 12px; border-radius: 3px; }
.btn:hover { background: var(--paper-deep); }
.btn.primary { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.seg { display: inline-flex; flex-wrap: wrap; border: 1px solid var(--paper-rule); border-radius: 3px; overflow: hidden; }
.seg button { border: 0; border-right: 1px solid var(--paper-rule); background: var(--paper); padding: 5px 10px; cursor: pointer; font: 12.5px var(--font-mono); }
.seg button:last-child { border-right: 0; }
.seg button[aria-pressed="true"] { background: var(--ink); color: var(--paper); }

/* ─── Plate frame ──────────────────────────────────────────── */
.topbar { position: sticky; top: 0; z-index: 10; display: flex; justify-content: space-between; align-items: center; gap: 12px; padding: 9px 22px; background: var(--paper); border-bottom: 1px solid var(--paper-rule); }
.topbar-left { display: flex; align-items: center; gap: 16px; min-width: 0; }
.topbar-back { font: 13px var(--font-mono); color: var(--ink-mute); text-decoration: none; white-space: nowrap; }
.topbar-title { font: 15px var(--font-display); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.topbar-title .icon { font: 600 11px var(--font-mono); letter-spacing: 0.1em; color: var(--red); margin-right: 6px; text-transform: uppercase; }
.lang-btn { border: 1px solid var(--paper-rule); background: var(--paper); border-radius: 3px; padding: 4px 12px; cursor: pointer; font-size: 14px; }
.main-content { max-width: 940px; margin: 0 auto; padding: 26px 28px 60px; }
.plate-meta { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px 18px; font: 12px/1.5 var(--font-mono); color: var(--ink-mute); border-bottom: 1px solid var(--paper-rule); padding-bottom: 8px; }
.plate-meta b { color: var(--red); font-weight: 600; }
.thread { display: inline-block; margin-left: 6px; padding: 0 6px; border: 1px solid var(--teal); color: var(--teal); border-radius: 2px; font: 600 11px var(--font-mono); }
.plate-title { font-size: 46px; line-height: 1.05; margin: 22px 0 10px; }
.plate-title em { color: var(--red); }
.plate-deck { font: italic 20px/1.45 var(--font-body); color: var(--ink-soft); margin: 0 0 22px; }
.info-box.lede { border-left: 3px solid var(--ochre); padding: 2px 0 2px 18px; margin: 0 0 22px; }
.info-box.lede p { margin: 0 0 12px; }
.preview { color: var(--ink-soft); font-size: 15.5px; }
.formula-group { display: flex; flex-wrap: wrap; gap: 6px 26px; justify-content: center; margin: 4px 0 18px; padding: 8px 0; border-top: 1px solid var(--paper-rule); border-bottom: 1px solid var(--paper-rule); }
.formula { font-size: 17px; overflow-x: auto; max-width: 100%; }
.learning-objectives { background: var(--paper-deep); border: 1px solid var(--paper-rule); padding: 12px 18px; margin: 0 0 26px; }
.learning-objectives-title, .threads-title, .example-label { font: 600 11px var(--font-mono); letter-spacing: 0.12em; text-transform: uppercase; color: var(--ink-mute); }
.learning-objectives ul { margin: 6px 0 0; padding-left: 20px; }
.section-title { font: 600 12px var(--font-mono); letter-spacing: 0.14em; text-transform: uppercase; color: var(--red); margin: 26px 0 8px; display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.model-chip { font: 11px var(--font-mono); letter-spacing: 0.02em; text-transform: none; color: var(--sienna); border: 1px dashed var(--sienna); padding: 1px 8px; border-radius: 2px; }
.figure { margin: 0 0 18px; }
.figure-caption { font: italic 14px/1.5 var(--font-body); color: var(--ink-mute); margin-top: 8px; }
h2 { font-size: 28px; margin: 34px 0 10px; }
.prose p { margin: 0 0 14px; }
.marginalia { border-left: 2px solid var(--plum); padding: 4px 0 4px 14px; font-size: 15px; color: var(--ink-soft); margin: 20px 0; }
dl.terms { display: grid; grid-template-columns: minmax(120px, 210px) 1fr; gap: 6px 18px; margin: 0; }
dl.terms dt { font: 600 14.5px var(--font-body); }
dl.terms dd { margin: 0; font-size: 15.5px; color: var(--ink-soft); }
.key-concept { margin: 26px 0; padding: 14px 18px; background: var(--ochre-tint); border-left: 3px solid var(--ochre); font-size: 17.5px; }
.threads, .sources { margin: 22px 0; font-size: 14.5px; color: var(--ink-soft); }
.threads ul, .sources ul { margin: 6px 0 0; padding-left: 20px; }
.sources .src { font: 12.5px var(--font-mono); color: var(--ink-mute); }
.example { border: 1px solid var(--paper-rule); background: var(--paper-vellum); padding: 12px 18px; margin: 22px 0; }
.example-title { font: 17px var(--font-display); margin: 4px 0 6px; }
.example ol { margin: 0; padding-left: 22px; font-size: 15.5px; }
.example li { margin: 3px 0; }
.section-break { height: 1px; background: var(--paper-rule); margin: 30px 0 14px; }
.nav-footer { display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; font: 13.5px var(--font-mono); }
.nav-footer a { text-decoration: none; }
.nav-report { color: var(--ink-mute) !important; }
.disclaimer { font: 12px/1.5 var(--font-body); color: var(--ink-faint); margin-top: 28px; }

/* ─── Workshop ─────────────────────────────────────────────── */
.ws { border: 1px solid var(--paper-rule); background: var(--paper-vellum); padding: 10px; }
.ws-fig { display: flex; flex-wrap: wrap; gap: 6px; }
.ws-panel { background: var(--fig-paper); border: 1px solid var(--fig-rule); overflow: hidden; }
.ws-panel canvas { display: block; touch-action: none; }
.ws-anim { display: flex; align-items: center; gap: 10px; margin: 8px 0 0; }
.ws-anim:empty { display: none; }
.ws-anim input { flex: 1; }
.ws-anim .t { font: 12px var(--font-mono); color: var(--ink-mute); min-width: 90px; }
.ws-body { display: grid; grid-template-columns: 1fr 260px; gap: 12px; margin-top: 10px; }
.ws-controls { display: flex; flex-direction: column; gap: 6px; }
.ctl { display: grid; grid-template-columns: minmax(130px, 210px) 1fr auto; align-items: center; gap: 10px; font-size: 14px; }
.ctl label { color: var(--ink-soft); }
.ctl input[type=range] { width: 100%; accent-color: var(--ink); }
.ctl output { font: 12.5px var(--font-mono); white-space: nowrap; min-width: 84px; text-align: right; }
.ctl .seg { grid-column: 2 / 4; }
.rail-stats { display: flex; flex-direction: column; gap: 3px; border-left: 1px solid var(--paper-rule); padding-left: 12px; }
.stat { display: flex; justify-content: space-between; gap: 10px; font-size: 13.5px; border-bottom: 1px dotted var(--paper-rule); padding: 2px 0; }
.stat .k { color: var(--ink-mute); }
.stat .v { font: 13px var(--font-mono); white-space: nowrap; }
.stat .v small { color: var(--ink-mute); font-size: 11px; }
.ws-note { margin-top: 10px; font-size: 15px; color: var(--ink-soft); }
.ws-note:empty, .ws-ch:empty { display: none; }
.ws-ch { margin-top: 10px; }
.ch-title { font: 600 11px var(--font-mono); letter-spacing: 0.12em; text-transform: uppercase; color: var(--green); }
.ws-ch ol { list-style: none; padding: 0; margin: 4px 0 0; }
.ws-ch li { display: flex; gap: 8px; align-items: baseline; font-size: 14.5px; padding: 2px 0; }
.ws-ch .box { display: inline-flex; width: 16px; height: 16px; border: 1px solid var(--ink-faint); border-radius: 2px; align-items: center; justify-content: center; font-size: 12px; flex: none; transform: translateY(2px); }
.ws-ch li.ok .box { background: var(--green); border-color: var(--green); color: var(--paper); }
.ws-ch li.was .box { border-color: var(--green); color: var(--green); }
table.ws-table { border-collapse: collapse; width: 100%; font: 12.5px var(--font-mono); background: var(--fig-paper); }
table.ws-table th, table.ws-table td { border-bottom: 1px solid var(--fig-rule); padding: 4px 8px; text-align: left; }
table.ws-table th { color: var(--ink-mute); font-weight: 600; }
table.ws-table tr.hl td { background: var(--ochre-tint); }
.ws-table-title { font: 600 11px var(--font-mono); padding: 6px 8px 0; }

/* ─── Practice, drills, projects ───────────────────────────── */
.try-block, .project-block, .mis-block, .journey { border: 1px solid var(--paper-rule); padding: 12px 16px; margin: 14px 0; background: var(--paper); }
.try-block:empty, .project-block:empty { display: none; }
.try-title, .pj-title { font: 600 11px var(--font-mono); letter-spacing: 0.12em; text-transform: uppercase; color: var(--blue); }
.try-q { margin: 6px 0; }
.try-row { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.try-row input { width: 150px; border: 1px solid var(--paper-rule); background: var(--input); color: var(--ink); padding: 5px 8px; font: 14px var(--font-mono); }
.try-row .u { font: 13px var(--font-mono); color: var(--ink-mute); }
.try-msg { font-size: 14.5px; color: var(--ink-soft); margin-top: 6px; min-height: 1.2em; }
.drill-head { font: 12px var(--font-mono); color: var(--ink-mute); }
.drill-done { font: 22px var(--font-display); margin: 6px 0 10px; }
.pj-checks { list-style: none; padding: 0; }
.pj-checks li { display: flex; gap: 8px; padding: 2px 0; }
.pj-checks .box { width: 16px; flex: none; text-align: center; }
.pj-checks li.ok .box { color: var(--green); }
.pj-checks li.no .box { color: var(--red); }
.pj-foot { display: flex; align-items: center; gap: 12px; font: 13px var(--font-mono); flex-wrap: wrap; }
.from { font: 11px var(--font-mono); color: var(--ink-faint); }
.jm-sum { font: 14px var(--font-mono); margin-bottom: 8px; }
.jm-key { font-size: 13px; color: var(--ink-mute); display: flex; align-items: center; gap: 6px; flex-wrap: wrap; margin-bottom: 10px; }
.jm-vol { margin: 6px 0; }
.jm-name { font: 13px var(--font-display); }
.jm-cells { display: flex; flex-wrap: wrap; gap: 3px; }
.jm-cell { display: inline-flex; width: 24px; height: 22px; border: 1px solid var(--paper-rule); align-items: center; justify-content: center; font: 10px var(--font-mono); color: var(--ink-mute); text-decoration: none; }
.jm-cell.open { background: var(--blue-tint); }
.jm-cell.read { background: var(--green); color: var(--paper); border-color: var(--green); }
.jm-cell.cap { background: var(--ochre); color: var(--paper); border-color: var(--ochre); }

/* ─── Knowledge check ──────────────────────────────────────── */
.quiz-container { margin-top: 30px; }
.quiz-head { display: flex; justify-content: space-between; align-items: baseline; border-bottom: 1px solid var(--ink); }
.quiz-head h3 { font-size: 24px; margin: 0 0 6px; }
.quiz-score { font: 13px var(--font-mono); color: var(--ink-mute); }
.quiz-q { padding: 10px 0; border-bottom: 1px solid var(--paper-rule); }
.quiz-q p { margin: 0 0 8px; }
.quiz-q .n { font: italic 15px var(--font-display); color: var(--red); margin-right: 8px; }
.quiz-opts { display: grid; grid-template-columns: 1fr 1fr; gap: 6px; }
.quiz-opts button { text-align: left; border: 1px solid var(--paper-rule); background: var(--paper); padding: 7px 10px; cursor: pointer; font-size: 15px; border-radius: 3px; }
.quiz-opts button:hover:not(:disabled) { background: var(--paper-deep); }
.quiz-opts button.right { background: var(--green-tint); border-color: var(--green); }
.quiz-opts button.wrong { background: var(--red-tint); border-color: var(--red); }
.quiz-opts button:disabled { cursor: default; color: var(--ink); }
.quiz-why { font-size: 14.5px; color: var(--ink-soft); margin-top: 6px; }
.quiz-foot { padding: 12px 0; }

@media (max-width: 760px) {
    .main-content { padding: 18px 16px 50px; }
    .plate-title { font-size: 34px; }
    .ws-body { grid-template-columns: 1fr; }
    .rail-stats { border-left: 0; padding-left: 0; }
    .ctl { grid-template-columns: 1fr auto; }
    .ctl label, .ctl .seg { grid-column: 1 / 3; }
    .quiz-opts { grid-template-columns: 1fr; }
    dl.terms { grid-template-columns: 1fr; }
    .topbar { padding: 8px 12px; }
}