/*
 * curated-en.css · English-specific typography & style refinements
 * Loaded AFTER curated.css; overrides only what differs.
 * Goals:
 *   1. English-native font stack (no CJK), serif headings for scholarly feel
 *   2. Tighter line-height (1.6 vs 1.7 for CJK)
 *   3. Classical typographic detail — kerning / ligatures / small-caps on labels
 *   4. Slightly more restrained palette — desaturated slate-blue, warmer amber
 */

:root {
  /* ─── English-first font stack ─── */
  --font-sans: "Inter", "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", Arial, sans-serif;
  --font-mono: "JetBrains Mono", "IBM Plex Mono", "Fira Code", "Consolas", monospace;
  --font-serif: "Source Serif Pro", "Source Serif 4", Merriweather, Charter, "Iowan Old Style", Georgia, serif;

  /* ─── Slightly desaturated palette for academic restraint ─── */
  --accent:   #e5a74a;   /* warm amber, less neon than #ffb74d */
  --accent-2: #88a9cc;   /* slate-blue, less cyan than #64b5f6 */
  --accent-3: #8fbe8f;   /* sage green */
  --accent-4: #cf8a8a;   /* dusty rose */
}

/* ─── Body: tighter leading + ligatures ─── */
body {
  line-height: 1.6;
  font-feature-settings: "kern" 1, "liga" 1, "calt" 1;
  text-rendering: optimizeLegibility;
}

/* ─── Background: subtler gradient (less saturated slate-blue) ─── */
body {
  background:
    radial-gradient(ellipse 1200px 600px at 0% 0%, rgba(136,169,204,0.07), transparent 60%),
    radial-gradient(ellipse 800px 400px at 100% 0%, rgba(229,167,74,0.05), transparent 60%),
    var(--bg-0);
}

/* ─── Hero: serif h1 with proper English display weight ─── */
.hero h1 {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 2.5em;
  line-height: 1.18;
  letter-spacing: -0.015em;
  /* override Chinese version's white→slate gradient with a more muted amber→cream */
  background: linear-gradient(135deg, #f5f2ed 0%, #c7bfb3 100%);
  -webkit-background-clip: text; background-clip: text;
}
.hero .kicker {
  letter-spacing: 0.18em;
  font-size: 0.76em;
}
.hero .lede {
  line-height: 1.58;
  font-size: 1.1em;
}

/* ─── Subsection headers: serif h2 ─── */
.subsect h2 {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 1.55em;
  letter-spacing: -0.005em;
  line-height: 1.25;
}
.subsect-num {
  font-family: var(--font-mono);
  font-feature-settings: "tnum" 1;   /* tabular figures — numbers align */
  letter-spacing: 0.02em;
}
.subsect-tag {
  font-variant: all-small-caps;
  letter-spacing: 0.08em;
  font-weight: 600;
  font-size: 0.72em;
}

/* ─── Body paragraphs: tighter leading, slight optical spacing ─── */
.subsect p {
  line-height: 1.6;
  font-size: 0.98em;
}
.subsect ul, .subsect ol { line-height: 1.55; }

/* ─── Callouts: labels in small-caps, body slightly looser ─── */
.callout {
  line-height: 1.55;
}
.callout .label {
  font-variant: all-small-caps;
  letter-spacing: 0.08em;
  font-size: 0.78em;
}

/* ─── Section nav (left sidebar): clean English tracking ─── */
.section-nav h3 {
  font-variant: all-small-caps;
  letter-spacing: 0.1em;
  font-size: 0.82em;
}
.section-nav a {
  letter-spacing: 0.005em;
  font-size: 0.9em;
}
.section-nav a .idnum {
  font-feature-settings: "tnum" 1;
}

/* ─── Active sidebar link: use desaturated gradient ─── */
.section-nav a.active {
  background: linear-gradient(90deg, rgba(229,167,74,0.08), transparent);
}

/* ─── Crumb bar ─── */
.topnav .crumbs { letter-spacing: 0.005em; }

/* ─── Buttons: subtle letter-spacing + English weight ─── */
.sect-nav-btn {
  font-weight: 600;
  letter-spacing: 0.01em;
  font-size: 0.92em;
}

/* ─── Formula block captions: italic serif (classic math aesthetic) ─── */
.formula-block .caption {
  font-family: var(--font-serif);
  font-style: italic;
  font-size: 0.88em;
  color: var(--text-dim);
  line-height: 1.5;
  letter-spacing: 0.005em;
}

/* ─── Comparison / triptych card headings ─── */
.eq-card h3, .compare-card h3, .ex-card .caption {
  font-family: var(--font-serif);
  font-weight: 600;
  letter-spacing: -0.005em;
}
.eq-card .desc, .compare-card ul li, .ex-card .desc {
  line-height: 1.55;
}

/* ─── Data tables: tabular nums, serif headers ─── */
table.data {
  font-variant-numeric: tabular-nums;
}
table.data thead th {
  font-variant: all-small-caps;
  letter-spacing: 0.08em;
  font-size: 0.88em;
}

/* ─── Stage-feature panel headings ─── */
.stage-feature h3 {
  font-family: var(--font-serif);
  font-weight: 600;
  letter-spacing: -0.005em;
}
.stage-feature .tag {
  font-variant: all-small-caps;
  letter-spacing: 0.1em;
  font-weight: 600;
}

/* ─── Progress text: tabular nums ─── */
.topnav .progress { font-variant-numeric: tabular-nums; }

/* ─── Equilibrium badges: English tracking ─── */
.eq-badge {
  font-variant: all-small-caps;
  letter-spacing: 0.06em;
  font-weight: 700;
}

/* ─── Footer: more spaced English text ─── */
.page-footer {
  line-height: 1.6;
  letter-spacing: 0.005em;
}

/* ─── Subtle refinement: refined progress-bar gradient ─── */
.topnav .progress-fill {
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
}

/* ─── Formula number: tabular figures + tighter tracking for English ─── */
.formula-block .eq-num {
  font-feature-settings: "tnum" 1;
  letter-spacing: 0;
}

/* ─── SWF label: small-caps + tabular nums for English ─── */
.swf-label {
  font-variant: all-small-caps;
  letter-spacing: 0.08em;
  font-feature-settings: "tnum" 1;
}