/* ══════════════════════════════════════════════════════════════
   SimpleOPD — Project Page
   Theme: ink navy + aurora accents (indigo/violet/cyan)
   ══════════════════════════════════════════════════════════════ */

:root {
  --bg: #f5f1e8;
  --bg-soft: #ebe5d8;
  --bg-card: rgba(255, 255, 255, 0.75);
  --bg-card-solid: #ffffff;
  --border: rgba(139, 116, 85, 0.15);
  --border-strong: rgba(139, 116, 85, 0.28);
  --text: #2d2416;
  --text-dim: #3d2e1f;
  --text-faint: #4d3a28;
  --accent-1: #d4a574;
  --accent-2: #c9a87d;
  --accent-3: #b8956a;
  --accent-ink: #8a5a22;
  --grad-ink: linear-gradient(120deg, #9a6424 0%, #8f5a1f 45%, #7d4d18 75%, #6b4013 100%);
  --gold: #d4a574;
  --grad: linear-gradient(120deg, #d4a574 0%, #c9a87d 45%, #b8956a 75%, #a08560 100%);
  --hero-bg: #2d2416;
  --hero-text: #f5f1e8;
  --font-display: "Fraunces", "Georgia", serif;
  --font-body: "Inter", -apple-system, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", "SF Mono", Consolas, monospace;
  --radius: 16px;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

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

html { scroll-behavior: smooth; scroll-padding-top: 84px; }

body {
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

::selection { background: rgba(212, 165, 116, 0.35); }

.container { max-width: 1080px; margin: 0 auto; padding: 0 28px; }

.mono { font-family: var(--font-mono); font-size: 0.88em; background: rgba(148, 163, 184, 0.12); padding: 0.15em 0.45em; border-radius: 6px; color: var(--text); }

/* ────────────────────────── NAVBAR ────────────────────────── */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  transition: background 0.4s var(--ease), box-shadow 0.4s var(--ease), border-color 0.4s var(--ease);
  border-bottom: 1px solid transparent;
  backdrop-filter: blur(14px);
}
.nav.scrolled {
  background: rgba(245, 241, 232, 0.95);
  border-bottom-color: var(--border);
  box-shadow: 0 4px 20px rgba(139, 116, 85, 0.08);
}
.nav-inner {
  max-width: 1180px; margin: 0 auto; padding: 0 28px;
  height: 68px; display: flex; align-items: center; justify-content: space-between; gap: 24px;
}
.nav-brand {
  font-family: var(--font-display); font-weight: 700; font-size: 1.35rem;
  color: #f5f1e8; text-decoration: none; letter-spacing: 0.2px;
}
.nav.scrolled .nav-brand { color: var(--text); }
.brand-accent { background: var(--grad); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }
.nav.scrolled .brand-accent { background: var(--grad-ink); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }
.nav-links { display: flex; gap: 4px; list-style: none; }
.nav-links a {
  color: rgba(245, 241, 232, 0.88); text-decoration: none; font-size: 0.92rem; font-weight: 500;
  padding: 8px 14px; border-radius: 999px; transition: color 0.25s, background 0.25s;
}
.nav.scrolled .nav-links a { color: var(--text-dim); }
.nav-links a:hover { color: #fff; background: rgba(148, 163, 184, 0.22); }
.nav.scrolled .nav-links a:hover { color: var(--text); background: rgba(148, 163, 184, 0.1); }
.nav-links a.active { color: #fff; background: rgba(212, 165, 116, 0.3); }
.nav.scrolled .nav-links a.active { color: var(--text); background: rgba(212, 165, 116, 0.16); }
.nav-cta {
  color: #fff; text-decoration: none; font-size: 0.88rem; font-weight: 600;
  padding: 9px 20px; border-radius: 999px;
  background: linear-gradient(120deg, #8c5f2e, #96693a);
  box-shadow: 0 6px 22px rgba(99, 102, 241, 0.4);
  transition: transform 0.25s var(--ease), box-shadow 0.25s var(--ease);
}
.nav-cta:hover { transform: translateY(-1px); box-shadow: 0 10px 28px rgba(99, 102, 241, 0.55); }

/* ────────────────────────── HERO ────────────────────────── */
.hero {
  position: relative; min-height: 100vh; display: flex; flex-direction: column;
  align-items: center; justify-content: center; text-align: center;
  padding: 150px 28px 90px; overflow: hidden;
  background: var(--hero-bg);
  color: var(--hero-text);
}
.hero-bg { position: absolute; inset: 0; width: 100%; height: 100%; z-index: 0; }
.hero-grid {
  position: absolute; inset: 0; z-index: 0; pointer-events: none;
  background-image:
    linear-gradient(rgba(148, 163, 184, 0.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(148, 163, 184, 0.05) 1px, transparent 1px);
  background-size: 56px 56px;
  -webkit-mask-image: radial-gradient(ellipse 75% 60% at 50% 40%, black 30%, transparent 75%);
  mask-image: radial-gradient(ellipse 75% 60% at 50% 40%, black 30%, transparent 75%);
}
.hero-content { position: relative; z-index: 2; max-width: 1000px; }
.hero-badge {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 9px 20px; border-radius: 999px; font-size: 0.85rem; font-weight: 500;
  color: #e8d4bf; background: rgba(212, 165, 116, 0.1);
  border: 1px solid rgba(212, 165, 116, 0.35);
  backdrop-filter: blur(8px); margin-bottom: 34px;
}
.badge-dot {
  width: 8px; height: 8px; border-radius: 50%; background: #4ade80;
  box-shadow: 0 0 0 0 rgba(74, 222, 128, 0.6); animation: pulse 2.2s infinite;
}
@keyframes pulse {
  0% { box-shadow: 0 0 0 0 rgba(74, 222, 128, 0.55); }
  70% { box-shadow: 0 0 0 10px rgba(74, 222, 128, 0); }
  100% { box-shadow: 0 0 0 0 rgba(74, 222, 128, 0); }
}
.hero-title {
  font-family: var(--font-display); font-weight: 700;
  font-size: clamp(3.4rem, 9vw, 6.2rem); line-height: 1.02; letter-spacing: -0.02em;
  margin-bottom: 26px;
}
.grad {
  background: var(--grad); -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(0 6px 40px rgba(212, 165, 116, 0.35));
}
.hero-title-sub {
  display: block; margin-top: 26px;
  font-size: clamp(1.05rem, 2.4vw, 1.5rem); font-weight: 500; letter-spacing: 0;
  color: #e8dcc9; line-height: 1.5;
}
.hero-tagline {
  max-width: 760px; margin: 0 auto 40px;
  font-size: 1.08rem; color: rgba(245, 241, 232, 0.85); line-height: 1.75;
}
.hero-tagline strong { color: var(--hero-text); font-weight: 600; }

/* authors */
.hero-authors {
  display: flex; flex-wrap: wrap; justify-content: center; gap: 6px 16px;
  max-width: 900px; margin: 0 auto 18px;
}
.author {
  font-size: 0.96rem; color: var(--hero-text); font-weight: 500;
  padding: 3px 0; transition: color 0.2s;
}
.author:hover { color: var(--accent-1); }
.author sup { color: #c9a87d; font-size: 0.7rem; margin-left: 2px; }
.hero-affil { font-size: 0.88rem; color: rgba(245, 241, 232, 0.7); margin-bottom: 44px; line-height: 1.8; }
.hero-affil sup { color: #c9a87d; }

/* buttons */
.hero-buttons { display: flex; justify-content: center; gap: 16px; flex-wrap: wrap; margin-bottom: 68px; }
.btn {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 14px 30px; border-radius: 999px; font-size: 0.95rem; font-weight: 600;
  text-decoration: none; transition: transform 0.3s var(--ease), box-shadow 0.3s var(--ease), background 0.3s;
}
.btn svg { width: 18px; height: 18px; transition: transform 0.3s var(--ease); }
.btn-primary {
  color: #fff; background: linear-gradient(120deg, #8c5f2e, #8c5f2e 60%, #7b4f9e);
  box-shadow: 0 10px 34px rgba(99, 102, 241, 0.45);
}
.btn-primary:hover { transform: translateY(-3px); box-shadow: 0 16px 44px rgba(99, 102, 241, 0.6); }
.btn-primary:hover svg { transform: translateX(4px); }
.btn-ghost {
  color: var(--hero-text); border: 1px solid rgba(245, 241, 232, 0.4);
  background: rgba(148, 163, 184, 0.06); backdrop-filter: blur(8px);
}
.btn-ghost:hover { transform: translateY(-3px); border-color: var(--accent-1); background: rgba(212, 165, 116, 0.1); box-shadow: 0 12px 30px rgba(0, 0, 0, 0.3); }
.btn-spark { color: var(--gold); animation: spark 2.4s ease-in-out infinite; display: inline-block; }
@keyframes spark {
  0%, 100% { transform: scale(1) rotate(0deg); opacity: 1; }
  50% { transform: scale(1.3) rotate(12deg); opacity: 0.7; }
}

/* hero metrics */
.hero-metrics {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px;
  max-width: 980px; margin: 0 auto;
}
.metric {
  position: relative; padding: 26px 18px 22px; border-radius: var(--radius);
  background: var(--bg-card); border: 1px solid var(--border);
  backdrop-filter: blur(10px);
  transition: transform 0.35s var(--ease), border-color 0.35s, background 0.35s;
  overflow: hidden;
}
.metric::before {
  content: ""; position: absolute; top: 0; left: 0; right: 0; height: 2.5px;
  background: var(--grad); opacity: 0.7; transform: scaleX(0); transform-origin: left;
  transition: transform 0.5s var(--ease);
}
.metric:hover { transform: translateY(-6px); border-color: var(--border-strong); background: rgba(255, 255, 255, 0.9); }
.metric:hover::before { transform: scaleX(1); }
.metric-num {
  display: inline-block; font-family: var(--font-display); font-weight: 700;
  font-size: 2.6rem; line-height: 1; letter-spacing: -0.01em;
  background: var(--grad-ink); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
}
.metric-unit { display: block; font-size: 0.85rem; color: var(--accent-ink); font-weight: 600; margin-top: 7px; }
.metric-label { display: block; margin-top: 7px; font-size: 0.78rem; color: var(--text-faint); line-height: 1.5; }

/* hero wave divider */
.hero-wave { position: absolute; bottom: -1px; left: 0; right: 0; z-index: 1; line-height: 0; }
.hero-wave svg { width: 100%; height: 110px; }

/* ────────────────────────── SECTIONS ────────────────────────── */
.section { position: relative; padding: 96px 0; }
.section-head { margin-bottom: 56px; }
.section-head h2 {
  font-family: var(--font-display); font-weight: 600;
  font-size: clamp(2rem, 4.5vw, 2.9rem); letter-spacing: -0.015em; margin-top: 10px;
}
.section-sub { margin-top: 14px; color: var(--text-dim); max-width: 720px; font-size: 1.02rem; }
.overline {
  display: inline-flex; align-items: center; gap: 10px;
  font-size: 0.76rem; font-weight: 700; letter-spacing: 0.18em; text-transform: uppercase;
  color: var(--accent-ink);
}
.overline::before { content: ""; width: 34px; height: 2px; background: var(--grad); border-radius: 2px; }

/* TL;DR */
.tldr-card {
  position: relative; padding: 48px 52px; border-radius: 24px;
  background: linear-gradient(135deg, rgba(212, 165, 116, 0.12), rgba(201, 168, 125, 0.10) 55%, rgba(184, 149, 106, 0.08));
  border: 1px solid var(--border);
  overflow: hidden;
  box-shadow: 0 4px 20px rgba(139, 116, 85, 0.06);
}
.tldr-card::after {
  content: ""; position: absolute; top: -120px; right: -120px; width: 320px; height: 320px;
  background: radial-gradient(circle, rgba(212, 165, 116, 0.16), transparent 70%);
  pointer-events: none;
}
.tldr-card p { margin-bottom: 18px; font-size: 1.04rem; color: var(--text); position: relative; z-index: 1; }
.tldr-card p:last-child { margin-bottom: 0; }
.tldr-card strong { color: var(--text); font-weight: 600; }
.tldr-card-icon {
  position: absolute; top: -34px; right: 42px; width: 96px; height: 96px; z-index: 0;
  display: flex; align-items: center; justify-content: center;
  font-size: 2.6rem; color: rgba(212, 165, 116, 0.22);
  transform: rotate(-8deg);
}
.highlight {
  background: linear-gradient(120deg, rgba(212, 165, 116, 0.28), rgba(201, 168, 125, 0.28));
  padding: 0.08em 0.35em; border-radius: 7px; font-weight: 700; color: var(--text);
}
.chip-teacher, .chip-student {
  display: inline-block; font-family: var(--font-mono); font-size: 0.84em;
  padding: 0.12em 0.5em; border-radius: 8px; font-weight: 600;
}
.chip-teacher {
  color: #a43d7a; background: rgba(184, 149, 106, 0.12);
  border: 1px solid rgba(184, 149, 106, 0.35);
}
.chip-student {
  color: #0e7490; background: rgba(212, 165, 116, 0.1);
  border: 1px solid rgba(212, 165, 116, 0.3);
}

/* Takeaways */
.takeaways { background: var(--bg-soft); }
.takeaway-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 22px; }
.takeaway-card {
  position: relative; padding: 34px 34px 30px; border-radius: var(--radius);
  background: var(--bg-card); border: 1px solid var(--border);
  transition: transform 0.4s var(--ease), border-color 0.4s, box-shadow 0.4s;
  overflow: hidden;
}
.takeaway-card::before {
  content: ""; position: absolute; inset: 0; opacity: 0;
  background: radial-gradient(600px circle at var(--mx, 50%) var(--my, 0%), rgba(212, 165, 116, 0.09), transparent 55%);
  transition: opacity 0.4s;
  pointer-events: none;
}
.takeaway-card:hover { transform: translateY(-6px); border-color: rgba(212, 165, 116, 0.5); box-shadow: 0 12px 36px rgba(139, 116, 85, 0.15); }
.takeaway-card:hover::before { opacity: 1; }
.tk-icon {
  font-family: var(--font-mono); font-size: 0.85rem; font-weight: 600;
  width: 44px; height: 44px; display: flex; align-items: center; justify-content: center;
  border-radius: 12px; margin-bottom: 20px;
  color: var(--accent-ink); background: rgba(212, 165, 116, 0.12);
  border: 1px solid rgba(212, 165, 116, 0.3);
  transition: transform 0.35s var(--ease);
}
.takeaway-card:hover .tk-icon { transform: rotate(-6deg) scale(1.08); }
.takeaway-card h3 { font-size: 1.18rem; font-weight: 600; margin-bottom: 12px; }
.takeaway-card p { color: var(--text-dim); font-size: 0.95rem; }

/* ────────────────────────── METHOD ────────────────────────── */
.method-block { margin-top: 64px; }
.method-block h3 {
  display: flex; align-items: center; gap: 14px;
  font-family: var(--font-display); font-weight: 600; font-size: 1.55rem; margin-bottom: 22px;
}
.method-num {
  font-family: var(--font-mono); font-size: 0.9rem; font-weight: 600;
  color: var(--accent-ink); background: rgba(212, 165, 116, 0.14);
  border: 1px solid rgba(212, 165, 116, 0.4); border-radius: 10px;
  padding: 5px 12px; flex-shrink: 0;
}
.method-block p { color: var(--text); margin-bottom: 14px; font-size: 1.02rem; }
.method-block p:last-child { margin-bottom: 0; }
.method-block em { color: var(--accent-ink); font-style: italic; }

/* mathjax */
mjx-container { overflow-x: auto; overflow-y: hidden; max-width: 100%; padding: 6px 0; }
mjx-container[display="true"] {
  margin: 26px 0 !important; padding: 14px 22px;
  background: rgba(255, 255, 255, 0.025);
  border: 1px solid var(--border); border-radius: 12px;
}
mjx-container[display="true"][jax="SVG"] { display: flex; justify-content: center; }

/* figures */
.figure-card {
  margin: 44px 0; padding: 30px; border-radius: 20px;
  background: var(--bg-card); border: 1px solid var(--border);
  transition: border-color 0.35s, transform 0.35s var(--ease);
}
.figure-card:hover { border-color: var(--border-strong); transform: translateY(-3px); }
figure { margin: 0; }
figure .fig-svg, figure .opd-diagram, figure svg { width: 100%; height: auto; display: block; }
figcaption {
  margin-top: 16px; padding-top: 0;
  font-size: 0.86rem; color: var(--text-dim); line-height: 1.7;
}
figcaption em { color: var(--text-faint); }
.fig-badge {
  display: inline-block; font-family: var(--font-mono); font-size: 0.7rem; font-weight: 600;
  color: var(--accent-ink); background: rgba(212, 165, 116, 0.12);
  border: 1px solid rgba(212, 165, 116, 0.35); border-radius: 999px;
  padding: 3px 11px; margin-right: 8px; vertical-align: 1px; letter-spacing: 0.05em;
}

/* method diagram svg styles */
.opd-diagram .diag-title { font-size: 15px; font-weight: 700; font-family: var(--font-body); }
.opd-diagram .diag-sub { font-size: 12px; font-family: var(--font-body); }
.opd-diagram .tok { filter: drop-shadow(0 3px 8px rgba(0, 0, 0, 0.35)); transition: filter 0.3s; }
.opd-diagram .tok-s { fill: rgba(212, 165, 116, 0.18); stroke: #d4a574; stroke-width: 1.3; }
.opd-diagram .tok-t { fill: rgba(184, 149, 106, 0.16); stroke: #b8956a; stroke-width: 1.3; }
.opd-diagram .tok-sh { fill: rgba(251, 191, 36, 0.1); stroke: #fbbf24; stroke-width: 1.3; stroke-dasharray: 4 3; }
.opd-diagram .tok-label { font-size: 13px; fill: #e2e8f0; text-anchor: middle; font-family: var(--font-mono); }
.opd-diagram .block-frame { transition: filter 0.4s; }
.opd-diagram .diag-block:hover .block-frame { filter: drop-shadow(0 0 22px rgba(212, 165, 116, 0.18)); }
.opd-diagram .flow-arrow, .opd-diagram .align-link { stroke-dasharray: 7 6; animation: dashflow 1.6s linear infinite; }
@keyframes dashflow { to { stroke-dashoffset: -26; } }
.dash-anim { animation: dashflow 1.8s linear infinite; }
.opd-diagram .diag-note { animation: floaty 4.5s ease-in-out infinite; }
@keyframes floaty {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-7px); }
}

/* algorithm block */
.algorithm {
  background: #0c1226; border: 1px solid var(--border); border-radius: 16px; overflow: hidden;
}
.algorithm-title {
  display: flex; align-items: center; gap: 12px;
  padding: 16px 24px; font-weight: 600; font-size: 0.98rem;
  color: #e6ecf5;
  border-bottom: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.03);
}
.algorithm-title .fig-badge {
  color: #d4a574; background: rgba(212, 165, 116, 0.14);
  border: 1px solid rgba(212, 165, 116, 0.45);
}
.algorithm-body {
  list-style: none; padding: 22px 24px; counter-reset: alg;
  font-family: var(--font-mono); font-size: 0.9rem; line-height: 2.05;
  color: #dbe3ee; overflow-x: auto;
}
.algorithm-body li { counter-increment: alg; white-space: nowrap; }
.algorithm-body li::before {
  content: counter(alg); display: inline-block; width: 22px; margin-right: 14px;
  color: #7c8aa0; font-size: 0.78rem; text-align: right;
}
.algorithm-body .ind1 { padding-left: 38px; }
.algorithm-body .ind2 { padding-left: 76px; }
.algorithm-body .kw { color: #f9a8d4; font-weight: 600; }
.algorithm-body .cmt { color: #9aa8bd; font-size: 0.82em; margin-left: 10px; }
.algorithm-body .cmt::selection, .algorithm-body .cmt *::selection { background: transparent; }

/* stabilization cards */
.stab-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; margin-top: 30px; }
.stab-card {
  padding: 32px; border-radius: var(--radius);
  background: var(--bg-card); border: 1px solid var(--border);
  transition: transform 0.35s var(--ease), border-color 0.35s;
}
.stab-card:hover { transform: translateY(-5px); border-color: rgba(201, 168, 125, 0.45); }
.stab-num {
  font-size: 1.6rem; margin-bottom: 14px; width: 52px; height: 52px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 14px; background: rgba(201, 168, 125, 0.12);
  border: 1px solid rgba(201, 168, 125, 0.35);
}
.stab-card h4 { font-size: 1.12rem; margin-bottom: 10px; }
.stab-card p { color: var(--text-dim); font-size: 0.94rem; }

/* ────────────────────────── SETUP ────────────────────────── */
.setup { background: #ebe5d8; }
.setup-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }
.setup-card {
  padding: 34px; border-radius: var(--radius);
  background: var(--bg-card); border: 1px solid var(--border);
  transition: transform 0.35s var(--ease), border-color 0.35s;
}
.setup-card:hover { transform: translateY(-4px); border-color: var(--border-strong); }
.setup-card-wide { grid-column: 1 / -1; }
.setup-card-head { display: flex; align-items: center; gap: 14px; margin-bottom: 18px; }
.setup-card-head h3 { font-size: 1.18rem; font-weight: 600; }
.setup-icon {
  width: 46px; height: 46px; display: flex; align-items: center; justify-content: center;
  font-size: 1.3rem; border-radius: 13px; flex-shrink: 0;
}
.setup-icon-teacher { background: rgba(184, 149, 106, 0.12); border: 1px solid rgba(184, 149, 106, 0.35); }
.setup-icon-student { background: rgba(212, 165, 116, 0.12); border: 1px solid rgba(212, 165, 116, 0.35); }
.setup-icon-data { background: rgba(251, 191, 36, 0.12); border: 1px solid rgba(251, 191, 36, 0.35); }
.setup-icon-config { background: rgba(201, 168, 125, 0.12); border: 1px solid rgba(201, 168, 125, 0.35); }
.setup-card p { color: var(--text-dim); font-size: 0.95rem; margin-bottom: 16px; }
.teacher-name {
  font-family: var(--font-mono); color: #a43d7a; font-weight: 600;
}
.setup-tags { list-style: none; display: flex; flex-wrap: wrap; gap: 8px; }
.setup-tags li {
  font-size: 0.78rem; font-weight: 500; padding: 6px 14px; border-radius: 999px;
  color: var(--accent-ink); background: rgba(212, 165, 116, 0.1); border: 1px solid rgba(212, 165, 116, 0.28);
}
.student-list { list-style: none; display: flex; flex-direction: column; gap: 10px; }
.student-list li { display: flex; align-items: center; gap: 12px; color: var(--text-dim); font-size: 0.9rem; }
.student-chip {
  font-family: var(--font-mono); font-size: 0.82rem; font-weight: 600;
  color: #0e7490; background: rgba(212, 165, 116, 0.1);
  border: 1px solid rgba(212, 165, 116, 0.3); padding: 4px 12px; border-radius: 8px;
}

/* data grid */
.data-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
.data-item {
  padding: 24px 20px; border-radius: 14px; text-align: center;
  background: rgba(255, 255, 255, 0.03); border: 1px solid var(--border);
  transition: transform 0.3s var(--ease), border-color 0.3s;
}
.data-item:hover { transform: translateY(-4px); border-color: rgba(251, 191, 36, 0.4); }
.data-count {
  display: block; font-family: var(--font-display); font-weight: 700;
  font-size: 2.2rem; color: var(--accent-ink); line-height: 1.1;
}
.data-name { display: block; font-weight: 600; font-size: 0.92rem; margin-top: 8px; }
.data-desc { display: block; font-size: 0.76rem; color: var(--text-faint); margin-top: 4px; }

/* config grid */
.config-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 14px; }
.config-item {
  padding: 16px 18px; border-radius: 12px;
  background: rgba(255, 255, 255, 0.03); border: 1px solid var(--border);
  transition: border-color 0.3s, transform 0.3s var(--ease);
}
.config-item:hover { border-color: rgba(201, 168, 125, 0.4); transform: translateY(-3px); }
.config-key { display: block; font-size: 0.72rem; letter-spacing: 0.06em; text-transform: uppercase; color: var(--text-faint); font-weight: 600; }
.config-val { display: block; margin-top: 6px; font-family: var(--font-mono); font-size: 0.88rem; color: var(--text); }
.config-note { margin-top: 20px; font-size: 0.88rem !important; color: var(--text-dim); padding-top: 18px; border-top: 1px dashed var(--border-strong); }
.config-note strong { color: var(--text); }

/* ────────────────────────── RESULTS ────────────────────────── */
.results-block { margin-bottom: 84px; }
.results-block h3 { font-family: var(--font-display); font-weight: 600; font-size: 1.5rem; margin-bottom: 24px; }
.prose p { color: var(--text); font-size: 1.02rem; margin-bottom: 14px; }
.prose p:last-child { margin-bottom: 0; }
.prose strong { color: var(--text); }

.fig-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; margin-top: 30px; align-items: start; }
.fig-grid-1 { grid-template-columns: 1.2fr 1fr; }
.fig-grid .figure-card, .fig-grid-1 .figure-card { margin: 0; }
.fig-svg { background: #0c1226; border-radius: 12px; }
.fx-title { font-size: 13.5px; font-weight: 700; fill: #cbd5e1; font-family: var(--font-body); }
.fig-svg .legend { font-size: 10.5px; font-family: var(--font-mono); }
.fig-svg .axis { font-size: 11px; font-family: var(--font-body); }
.series polyline { filter: drop-shadow(0 0 6px rgba(212, 165, 116, 0.35)); }

/* bar figure */
.bar-fig .bar-base { fill: rgba(148, 163, 184, 0.25); }
.bar-fig .bar-opd { fill: url(#gBar); filter: drop-shadow(0 6px 18px rgba(99, 102, 241, 0.5)); }
.bar-fig .bar-val { font-size: 14px; font-weight: 700; fill: #94a3b8; font-family: var(--font-mono); }
.bar-fig .bar-val-opd { fill: #e0e7ff; }
.bar-fig .bar-label { font-size: 11px; fill: #94a3b8; font-family: var(--font-body); }
.bar-fig .bar-group:hover .bar { transform: translateY(-4px); transition: transform 0.3s var(--ease); }
.bar-fig .bar-group:hover .bar-glow rect { opacity: 1; animation: glowpulse 1.6s ease-in-out infinite; }
@keyframes glowpulse {
  0%, 100% { opacity: 0.15; }
  50% { opacity: 0.6; }
}

/* tables */
.table-card {
  padding: 30px; border-radius: 18px;
  background: var(--bg-card); border: 1px solid var(--border);
}
.table-card-wide { margin-top: 30px; }
.table-title { font-size: 1.05rem; font-weight: 600; margin-bottom: 18px; }
.table-wrap { overflow-x: auto; }
.res-table {
  width: 100%; border-collapse: collapse; font-size: 0.92rem; min-width: 480px;
}
.res-table th {
  text-align: left; font-size: 0.78rem; letter-spacing: 0.07em; text-transform: uppercase;
  color: var(--text-faint); font-weight: 600;
  padding: 12px 16px; border-bottom: 1px solid var(--border-strong);
  white-space: nowrap;
}
.res-table td {
  padding: 13px 16px; border-bottom: 1px solid rgba(148, 163, 184, 0.08);
  color: var(--text); white-space: nowrap;
  font-variant-numeric: tabular-nums;
}
.res-table tbody tr { transition: background 0.25s; }
.res-table tbody tr:hover { background: rgba(212, 165, 116, 0.08); }
.res-table .row-teacher td { color: #a43d7a; }
.res-table .row-base td { color: #57616e; }
.res-table .row-opd td { color: #3b3a87; }
.res-table .delta { color: #15803d; font-weight: 700; }
.tag {
  display: inline-block; font-size: 0.66rem; font-weight: 700; letter-spacing: 0.05em;
  padding: 2px 9px; border-radius: 999px; margin-left: 6px; vertical-align: 2px;
  text-transform: uppercase;
}
.tag-teacher { color: #a43d7a; background: rgba(184, 149, 106, 0.14); border: 1px solid rgba(184, 149, 106, 0.35); }
.tag-base { color: #57616e; background: rgba(148, 163, 184, 0.12); border: 1px solid rgba(148, 163, 184, 0.25); }
.table-note { margin-top: 16px; font-size: 0.84rem; color: var(--text-dim); line-height: 1.7; }
.table-note strong { color: var(--accent-ink); }

/* ────────────────────────── ANALYSIS ────────────────────────── */
.analysis { background: #ebe5d8; }
.analysis-block { margin-bottom: 70px; }
.analysis-block h3 { font-family: var(--font-display); font-weight: 600; font-size: 1.45rem; margin-bottom: 20px; }
.analysis-prose p { color: var(--text-dim); font-size: 1rem; }
.analysis-prose {
  padding: 30px; border-radius: 18px; border: 1px solid var(--border);
  background: var(--bg-card);
  display: flex; align-items: center; min-height: 100%;
}
.analysis-prose strong { color: var(--text); }

/* ────────────────────────── CONCLUSION ────────────────────────── */
.conclusion-card {
  position: relative; padding: 54px 58px; border-radius: 24px; overflow: hidden;
  background: linear-gradient(135deg, rgba(212, 165, 116, 0.10), rgba(201, 168, 125, 0.08) 55%, rgba(184, 149, 106, 0.06));
  border: 1px solid var(--border);
}
.conclusion-card::before {
  content: ""; position: absolute; top: -140px; left: -100px; width: 380px; height: 380px;
  background: radial-gradient(circle, rgba(201, 168, 125, 0.16), transparent 70%);
  pointer-events: none;
}
.conclusion-card p { font-size: 1.04rem; color: var(--text); margin-bottom: 20px; position: relative; z-index: 1; }
.conclusion-card strong { color: var(--text); }
.conclusion-list { list-style: none; margin: 28px 0; display: flex; flex-direction: column; gap: 14px; position: relative; z-index: 1; }
.conclusion-list li {
  display: flex; align-items: center; gap: 16px;
  padding: 18px 22px; border-radius: 14px;
  background: rgba(255, 255, 255, 0.04); border: 1px solid var(--border);
  font-size: 1rem;
  transition: transform 0.3s var(--ease), border-color 0.3s;
}
.conclusion-list li:hover { transform: translateX(6px); border-color: rgba(201, 168, 125, 0.45); }
.concl-num {
  width: 42px; height: 42px; flex-shrink: 0; display: flex; align-items: center; justify-content: center;
  font-size: 1.15rem; border-radius: 11px;
  background: rgba(201, 168, 125, 0.13); border: 1px solid rgba(201, 168, 125, 0.4);
}
.conclusion-footer { margin-top: 30px; display: flex; gap: 10px; flex-wrap: wrap; position: relative; z-index: 1; }
.chip-note {
  display: inline-block; font-family: var(--font-mono); font-size: 0.82rem;
  color: var(--accent-ink); background: rgba(251, 191, 36, 0.1);
  border: 1px dashed rgba(251, 191, 36, 0.45);
  padding: 8px 16px; border-radius: 999px;
}

/* ────────────────────────── CITATION ────────────────────────── */
.citation-card { border-radius: 18px; overflow: hidden; border: 1px solid var(--border); }
.citation-toolbar {
  display: flex; align-items: center; gap: 8px;
  padding: 14px 20px; background: rgba(255, 255, 255, 0.04);
  border-bottom: 1px solid var(--border);
}
.citation-toolbar .dot { width: 12px; height: 12px; border-radius: 50%; }
.dot.red { background: #f87171; }
.dot.yellow { background: #fbbf24; }
.dot.green { background: #34d399; }
.citation-filename { margin-left: 10px; font-family: var(--font-mono); font-size: 0.84rem; color: var(--text-dim); }
.copy-btn {
  margin-left: auto; font-family: var(--font-body); font-size: 0.8rem; font-weight: 600;
  color: var(--text); background: rgba(148, 163, 184, 0.1);
  border: 1px solid var(--border-strong); border-radius: 8px;
  padding: 7px 16px; cursor: pointer; transition: all 0.25s;
}
.copy-btn:hover { border-color: var(--accent-1); color: var(--accent-ink); background: rgba(212, 165, 116, 0.12); }
.copy-btn.copied { color: #15803d; border-color: rgba(21, 128, 61, 0.5); }
.citation-code {
  padding: 26px 28px; overflow-x: auto;
  background: #0a0f20; font-family: var(--font-mono); font-size: 0.88rem; line-height: 1.85;
  color: #dbe3ee;
}
.citation-note { padding: 18px 26px; font-size: 0.86rem; color: var(--text-dim); border-top: 1px dashed var(--border); }

/* ────────────────────────── FOOTER ────────────────────────── */
.footer { padding: 60px 0 70px; border-top: 1px solid var(--border); background: #2d2416; }
.footer-inner { text-align: center; }
.footer-brand { font-family: var(--font-display); font-size: 1.6rem; font-weight: 700; margin-bottom: 10px; color: #f5f1e8; }
.footer-text { color: #e8dcc9; font-size: 0.92rem; }
.footer-meta { color: #b7a68e; font-size: 0.78rem; margin-top: 22px; max-width: 560px; margin-left: auto; margin-right: auto; line-height: 1.7; }

/* back to top */
.back-to-top {
  position: fixed; right: 26px; bottom: 26px; z-index: 90;
  width: 46px; height: 46px; border-radius: 13px; border: 1px solid var(--border-strong);
  background: rgba(255, 255, 255, 0.95); color: var(--text); font-size: 1.15rem;
  cursor: pointer; opacity: 0; pointer-events: none; transform: translateY(14px);
  transition: all 0.35s var(--ease); backdrop-filter: blur(8px);
}
.back-to-top.visible { opacity: 1; pointer-events: auto; transform: translateY(0); }
.back-to-top:hover { background: rgba(212, 165, 116, 0.2); border-color: var(--accent-1); transform: translateY(-3px); }

/* ────────────────────────── LIGHTBOX ────────────────────────── */
.figure-card img, figure img {
  cursor: zoom-in;
}
.lightbox {
  position: fixed; inset: 0; z-index: 200;
  display: flex; align-items: center; justify-content: center;
  background: rgba(13, 11, 6, 0.92);
  opacity: 0; pointer-events: none; transition: opacity 0.3s var(--ease);
}
.lightbox.open { opacity: 1; pointer-events: auto; }
.lightbox img {
  max-width: 92vw; max-height: 92vh;
  border-radius: 12px; box-shadow: 0 24px 80px rgba(0, 0, 0, 0.6);
  cursor: zoom-out;
}

/* ────────────────────────── REVEAL ────────────────────────── */
.reveal {
  opacity: 0; transform: translateY(34px);
  transition: opacity 0.9s var(--ease), transform 0.9s var(--ease);
  transition-delay: var(--d, 0s);
}
.reveal.in { opacity: 1; transform: none; }
.takeaway-card[data-t="1"] { --d: 0s; }
.takeaway-card[data-t="2"] { --d: 0.1s; }
.takeaway-card[data-t="3"] { --d: 0.2s; }
.takeaway-card[data-t="4"] { --d: 0.3s; }

/* draw-in animation for SVG series */
@keyframes drawin { from { stroke-dashoffset: var(--len, 900); } to { stroke-dashoffset: 0; } }
.series polyline {
  stroke-dasharray: var(--len, 900); stroke-dashoffset: var(--len, 900);
}
.in .series polyline, .reveal.in .series polyline { animation: drawin 2.2s var(--ease) forwards 0.3s; }

/* reduced motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.01ms !important; animation-iteration-count: 1 !important; transition-duration: 0.01ms !important; }
  .reveal { opacity: 1; transform: none; }
  .series polyline { stroke-dashoffset: 0; }
}

/* ────────────────────────── RESPONSIVE ────────────────────────── */
@media (max-width: 960px) {
  .hero-metrics { grid-template-columns: repeat(2, 1fr); }
  .takeaway-grid, .setup-grid, .stab-grid, .fig-grid, .fig-grid-1 { grid-template-columns: 1fr; }
  .data-grid { grid-template-columns: repeat(2, 1fr); }
  .config-grid { grid-template-columns: repeat(2, 1fr); }
  .tldr-card, .conclusion-card { padding: 36px 28px; }
  .nav-links { display: none; }
}
@media (max-width: 560px) {
  .hero-metrics { grid-template-columns: 1fr; }
  .data-grid { grid-template-columns: 1fr; }
  .hero { padding-top: 120px; }
}

/* ────────────────────────── LANGUAGE SWITCH ────────────────────────── */
.lang-switch {
  display: flex; align-items: center; gap: 6px;
  background: transparent; border: 1px solid rgba(245, 241, 232, 0.4);
  border-radius: 999px; padding: 6px 14px; cursor: pointer;
  font-family: var(--font-body); font-size: 0.85rem; font-weight: 500;
  transition: border-color 0.25s, background 0.25s;
}
.nav.scrolled .lang-switch { border-color: var(--border-strong); }
.lang-switch:hover { border-color: var(--accent-1); background: rgba(212, 165, 116, 0.08); }
.lang-option {
  color: rgba(245, 241, 232, 0.8); cursor: pointer; transition: color 0.25s;
  padding: 2px 6px; border-radius: 4px;
}
.nav.scrolled .lang-option { color: var(--text-faint); }
.lang-option.active { color: var(--accent-1); font-weight: 600; }
.nav.scrolled .lang-option.active { color: var(--accent-ink); }
.lang-option:hover:not(.active) { color: #fff; }
.nav.scrolled .lang-option:hover:not(.active) { color: var(--text); }
.lang-divider { color: rgba(245, 241, 232, 0.45); }
.nav.scrolled .lang-divider { color: var(--border-strong); }

/* Language-specific content */
[lang="zh"] .en-only { display: none; }
[lang="en"] .zh-only { display: none; }