/* ========== Reset & Base ========== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --accent: #2563eb;
  --accent-light: #dbeafe;
  --accent-dark: #1e40af;
  --bg: #ffffff;
  --bg-alt: #f8fafb;
  --text: #1e293b;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --card-shadow: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.06);
  --section-gap: 5rem;
  --max-w: 960px;
}

html { scroll-behavior: smooth; }

body {
  font-family: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  font-size: 16px;
}

/* ========== Typography ========== */
h1, h2, h3 { font-family: 'Source Serif 4', Georgia, serif; font-weight: 700; line-height: 1.3; }
h1 { font-size: 2.2rem; }
h2 { font-size: 1.6rem; margin-bottom: 1rem; }
h3 { font-size: 1.15rem; margin-bottom: 0.5rem; }

.smallcaps {
  font-variant: small-caps;
  letter-spacing: 0.06em;
  font-weight: 700;
}

a { color: var(--accent-dark); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ========== Layout ========== */
.container { max-width: var(--max-w); margin: 0 auto; padding: 0 1.5rem; }

section {
  padding: var(--section-gap) 0;
}
section:nth-child(even) { background: var(--bg-alt); }

/* ========== Navigation ========== */
nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  padding: 0.7rem 0;
}
nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
nav .brand {
  font-family: 'Source Serif 4', Georgia, serif;
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--accent-dark);
  font-variant: small-caps;
  letter-spacing: 0.06em;
}
nav .nav-links { display: flex; gap: 1.5rem; list-style: none; }
nav .nav-links a {
  font-size: 0.88rem;
  color: var(--text-muted);
  font-weight: 500;
  transition: color 0.2s;
}
nav .nav-links a:hover { color: var(--accent-dark); text-decoration: none; }

/* ========== Hero ========== */
.hero {
  text-align: center;
  padding: 4.5rem 0 3.5rem;
}
.hero h1 { margin-bottom: 1.2rem; font-size: 2.4rem; }
.hero .authors {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-bottom: 0.4rem;
}
.hero .authors a { color: var(--text); font-weight: 500; }
.hero .affiliations {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
}
.hero .venue {
  display: inline-block;
  background: var(--accent-light);
  color: var(--accent-dark);
  font-weight: 600;
  font-size: 0.85rem;
  padding: 0.25rem 0.8rem;
  border-radius: 999px;
  margin-bottom: 1.5rem;
}
.hero .links {
  display: flex;
  justify-content: center;
  gap: 0.8rem;
  flex-wrap: wrap;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.5rem 1.1rem;
  border-radius: 6px;
  font-size: 0.88rem;
  font-weight: 600;
  transition: background 0.2s, color 0.2s;
  border: 1px solid var(--border);
  color: var(--text);
  background: var(--bg);
}
.btn:hover { background: var(--accent-light); color: var(--accent-dark); text-decoration: none; }
.btn.primary { background: var(--accent); color: #fff; border-color: var(--accent); }
.btn.primary:hover { background: var(--accent-dark); }
.btn svg { width: 16px; height: 16px; }

/* ========== TL;DR ========== */
.tldr {
  text-align: center;
  padding: 2.5rem 0 3rem;
  border-bottom: 1px solid var(--border);
}
.tldr p {
  font-size: 1.15rem;
  max-width: 740px;
  margin: 0 auto;
  color: var(--text);
}
.tldr .highlight {
  color: var(--accent-dark);
  font-weight: 600;
}

/* ========== Section Headers ========== */
.section-header {
  text-align: center;
  margin-bottom: 2.5rem;
}
.section-header p {
  color: var(--text-muted);
  max-width: 640px;
  margin: 0.5rem auto 0;
  font-size: 0.95rem;
}

/* ========== Problem / Side-by-Side ========== */
.side-by-side {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin-top: 1.5rem;
}

.user-panel {
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
  background: var(--bg);
  box-shadow: var(--card-shadow);
  transition: box-shadow 0.25s;
}
.user-panel:hover { box-shadow: 0 4px 12px rgba(0,0,0,0.1); }

.user-panel .panel-header {
  padding: 0.8rem 1rem;
  font-weight: 700;
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.user-panel.novice .panel-header { background: #fef3c7; color: #92400e; }
.user-panel.advanced .panel-header { background: #d1fae5; color: #065f46; }

.panel-body { padding: 1rem; }

.turn {
  margin-bottom: 1rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}
.turn:last-child { border-bottom: none; margin-bottom: 0; padding-bottom: 0; }
.turn-label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-bottom: 0.3rem;
}
.turn-text { font-size: 0.88rem; line-height: 1.6; }

.metric-row {
  display: flex;
  gap: 0.6rem;
  margin-top: 0.6rem;
  flex-wrap: wrap;
}
.metric-badge {
  font-size: 0.72rem;
  font-weight: 600;
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  background: #f1f5f9;
  color: var(--text-muted);
}
.metric-badge.good { background: #d1fae5; color: #065f46; }
.metric-badge.bad { background: #fee2e2; color: #991b1b; }

/* ========== How It Works ========== */
.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  margin-top: 1.5rem;
}
.step-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.5rem;
  box-shadow: var(--card-shadow);
  position: relative;
}
.step-card .step-num {
  font-family: 'Source Serif 4', Georgia, serif;
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent-light);
  position: absolute;
  top: 0.8rem;
  right: 1rem;
}
.step-card h3 { color: var(--accent-dark); }
.step-card p { font-size: 0.88rem; color: var(--text-muted); }

/* ========== Metrics Cards ========== */
.metric-cards {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
  margin-top: 1.5rem;
}
.metric-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.2rem;
  box-shadow: var(--card-shadow);
  text-align: center;
}
.metric-card .metric-icon {
  font-size: 1.8rem;
  margin-bottom: 0.5rem;
}
.metric-card h3 { font-size: 0.95rem; margin-bottom: 0.3rem; }
.metric-card p { font-size: 0.8rem; color: var(--text-muted); }
.metric-card .formula {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.75rem;
  background: var(--bg-alt);
  padding: 0.4rem;
  border-radius: 4px;
  margin-top: 0.5rem;
  color: var(--accent-dark);
}

/* ========== IU Init Diagram ========== */
.iu-init-diagram {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin-top: 1rem;
}
.iu-init-col { text-align: center; flex: 1; }
.iu-init-label {
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  display: inline-block;
  margin-bottom: 0.4rem;
}
.iu-init-label.novice { background: #fef3c7; color: #92400e; }
.iu-init-label.intermediate { background: #dbeafe; color: #1e40af; }
.iu-init-label.advanced { background: #d1fae5; color: #065f46; }
.iu-init-nodes {
  display: flex;
  gap: 4px;
  justify-content: center;
  margin-bottom: 0.3rem;
}
.iu-dot {
  width: 18px;
  height: 18px;
  border-radius: 4px;
  display: inline-block;
}
.iu-dot.unaware { background: #e2e8f0; }
.iu-dot.struggling { background: #fecaca; }
.iu-dot.partial { background: #fde68a; }
.iu-dot.knows_well { background: #6ee7b7; }
.iu-init-caption { font-size: 0.7rem; color: var(--text-muted); }
.iu-init-note {
  text-align: center;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.5rem;
  font-style: italic;
}

/* ========== Step Phase Labels ========== */
.step-phase {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.15rem 0.6rem;
  border-radius: 999px;
  background: var(--accent-light);
  color: var(--accent-dark);
  margin-bottom: 0.6rem;
}

/* ========== Per-Turn Flow Diagram ========== */
.perturn-flow {
  display: flex;
  align-items: stretch;
  gap: 0;
  margin-top: 1rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
  background: var(--bg);
}
.perturn-step {
  flex: 1;
  padding: 0.7rem 0.65rem;
  font-size: 0.78rem;
  line-height: 1.5;
  border-right: 1px solid var(--border);
}
.perturn-step:last-child { border-right: none; }
.perturn-step p { margin: 0.3rem 0; }
.perturn-external { opacity: 0.8; }
.perturn-header {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  margin-bottom: 0.4rem;
}
.perturn-circle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  font-weight: 700;
  font-size: 0.72rem;
  color: #fff;
  flex-shrink: 0;
}
.perturn-title {
  font-weight: 700;
  font-size: 0.82rem;
}
.perturn-arrow {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  color: #94a3b8;
  flex: 0 0 20px;
  background: var(--bg-alt);
}
.perturn-constraints {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  margin-top: 0.4rem;
}
.perturn-constraint {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.75rem;
  color: #334155;
}
.iu-swatch {
  display: inline-block;
  width: 12px;
  height: 12px;
  border-radius: 3px;
  flex-shrink: 0;
}
.iu-swatch.unaware { background: #f1f5f9; border: 1.5px solid #94a3b8; }
.iu-swatch.struggling { background: #fee2e2; border: 1.5px solid #991b1b; }
.iu-swatch.partial { background: #fef3c7; border: 1.5px solid #92400e; }
.iu-swatch.knows_well { background: #d1fae5; border: 1.5px solid #065f46; }

.perturn-ext-box {
  margin-top: 0.4rem;
  padding: 0.5rem 0.6rem;
  border: 1.5px dashed #cbd5e1;
  border-radius: 6px;
  background: #f9fafb;
}
.perturn-ext-label {
  font-size: 0.68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: #94a3b8;
}
.perturn-ext-box p {
  font-size: 0.75rem;
  color: #64748b;
  margin: 0.2rem 0 0;
}

.perturn-signal {
  padding: 0.4rem 0.5rem;
  background: #f8fafc;
  border: 1px solid #e2e8f0;
  border-radius: 6px;
  margin-top: 0.4rem;
}
.perturn-signal-label {
  font-size: 0.68rem;
  font-weight: 700;
  color: #475569;
  margin-bottom: 0.15rem;
}
.perturn-signal p { font-size: 0.75rem; margin: 0; }
.perturn-signal code {
  font-size: 0.68rem;
  color: #64748b;
  font-family: 'IBM Plex Mono', monospace;
}

.perturn-rules {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  margin-top: 0.3rem;
}
.perturn-rule {
  font-size: 0.73rem;
  color: #334155;
  line-height: 1.45;
  padding: 0.2rem 0;
  border-bottom: 1px solid #f1f5f9;
}
.perturn-rule:last-child { border-bottom: none; }

/* Per-turn before/after example */
.perturn-example {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  margin-top: 1rem;
  padding: 0.8rem 1rem;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 8px;
}
.perturn-graph-col { text-align: center; }
.perturn-graph-label {
  font-size: 0.75rem;
  font-weight: 700;
  color: #475569;
  margin-bottom: 0.3rem;
}
.perturn-graph-col svg {
  width: 160px;
  height: auto;
}
.perturn-graph-arrow {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.1rem;
  font-size: 1.4rem;
  color: #0f172a;
}
.perturn-graph-arrow small {
  font-size: 0.7rem;
  font-weight: 600;
}
.perturn-graph-explanation {
  flex: 0 0 auto;
  max-width: 260px;
  padding-left: 1rem;
  border-left: 1px solid var(--border);
}
.perturn-graph-explanation p {
  font-size: 0.78rem;
  line-height: 1.5;
  color: #334155;
  margin: 0.3rem 0;
}

@media (max-width: 768px) {
  .perturn-flow {
    flex-direction: column;
  }
  .perturn-step { border-right: none; border-bottom: 1px solid var(--border); }
  .perturn-step:last-child { border-bottom: none; }
  .perturn-arrow {
    flex: 0 0 24px;
    font-size: 1rem;
    transform: rotate(90deg);
  }
  .perturn-example {
    flex-direction: column;
    gap: 0.8rem;
  }
  .perturn-graph-explanation {
    border-left: none;
    border-top: 1px solid var(--border);
    padding-left: 0;
    padding-top: 0.8rem;
    max-width: 100%;
  }
}

/* ========== Update Rules (Drivers / Constraints) ========== */
.update-rules {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.8rem;
  margin-top: 1rem;
}
.update-rule {
  padding: 0.7rem 0.8rem;
  border-radius: 8px;
  font-size: 0.82rem;
  line-height: 1.55;
}
.update-rule-label {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 0.3rem;
}
.update-rule.driver {
  background: #ecfdf5;
  border: 1px solid #a7f3d0;
}
.update-rule.driver .update-rule-label { color: #065f46; }
.update-rule.constraint {
  background: #fff7ed;
  border: 1px solid #fed7aa;
}
.update-rule.constraint .update-rule-label { color: #9a3412; }
.update-rule p { color: var(--text-muted); margin: 0; }

/* ========== Simulation Loop Diagram ========== */
.sim-loop {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.3rem;
  margin-top: 1rem;
  flex-wrap: wrap;
}
.sim-loop-step {
  text-align: center;
  padding: 0.5rem;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 8px;
  min-width: 100px;
  flex: 1;
}
.sim-loop-icon { font-size: 1.3rem; margin-bottom: 0.2rem; }
.sim-loop-text { font-size: 0.72rem; line-height: 1.4; }
.sim-loop-arrow {
  font-size: 1.1rem;
  color: var(--accent);
  font-weight: 700;
  flex-shrink: 0;
}

.state-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.3rem;
  margin-top: 0.8rem;
}
.state-chip {
  font-size: 0.7rem;
  font-weight: 600;
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
}
.state-chip.unaware { background: #f1f5f9; color: #94a3b8; }
.state-chip.struggling { background: #fee2e2; color: #991b1b; }
.state-chip.partial { background: #fef3c7; color: #92400e; }
.state-chip.knows_well { background: #d1fae5; color: #065f46; }
.state-arrow {
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* ========== Conversation Examples ========== */
.example-controls {
  display: flex;
  gap: 1.5rem;
  margin-bottom: 1.2rem;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
}
.example-select-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.example-select-row label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
  white-space: nowrap;
}
.example-select-row select {
  font-family: inherit;
  font-size: 0.85rem;
  padding: 0.4rem 0.8rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--bg);
  color: var(--text);
  cursor: pointer;
  min-width: 200px;
}

.example-context {
  background: var(--accent-light);
  border-radius: 8px;
  padding: 0.8rem 1rem;
  margin-bottom: 1.2rem;
  font-size: 0.88rem;
  line-height: 1.6;
}
.example-context .ctx-label {
  font-weight: 700;
  color: var(--accent-dark);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 0.2rem;
}
.example-context .ctx-level {
  display: inline-block;
  padding: 0.1rem 0.5rem;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 700;
  margin-left: 0.5rem;
}
.ctx-level.novice { background: #fef3c7; color: #92400e; }
.ctx-level.intermediate { background: #dbeafe; color: #1e40af; }
.ctx-level.advanced { background: #d1fae5; color: #065f46; }

/* Conversation comparison layout */
.conv-comparison {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-bottom: 2rem;
}
.conv-column {
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
  background: var(--bg);
  box-shadow: var(--card-shadow);
  display: flex;
  flex-direction: column;
}
.conv-column-header {
  padding: 0.7rem 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.4rem;
}
.conv-column-header.knowsim-header {
  background: linear-gradient(135deg, #dbeafe, #ede9fe);
  border-bottom: 2px solid var(--accent);
}
.conv-column-header.baseline-header {
  background: #f1f5f9;
  border-bottom: 2px solid #94a3b8;
}
.conv-column-header.human-header {
  background: linear-gradient(135deg, #fef3c7, #fde68a);
  border-bottom: 2px solid #f59e0b;
}
.method-label {
  font-weight: 700;
  font-size: 0.9rem;
}
.metric-summary {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
}
.metric-summary .m-badge {
  font-size: 0.7rem;
  font-weight: 600;
  padding: 0.1rem 0.45rem;
  border-radius: 3px;
  background: rgba(255,255,255,0.7);
  white-space: nowrap;
}

/* Chat bubbles */
.conv-scroll {
  flex: 1;
  overflow-y: auto;
  max-height: 600px;
  padding: 0.8rem;
}
.chat-bubble {
  margin-bottom: 0.8rem;
  display: flex;
  flex-direction: column;
}
.chat-bubble .cb-role {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 0.2rem;
}
.chat-bubble.user .cb-role { color: #6366f1; }
.chat-bubble.assistant .cb-role { color: var(--accent-dark); }

.chat-bubble .cb-content {
  font-size: 0.84rem;
  line-height: 1.65;
  padding: 0.6rem 0.8rem;
  border-radius: 8px;
  max-width: 100%;
  overflow-wrap: break-word;
}
.chat-bubble.user .cb-content {
  background: #eef2ff;
  border: 1px solid #c7d2fe;
}
.chat-bubble.assistant .cb-content {
  background: #eff6ff;
  border: 1px solid #bfdbfe;
}
/* MathML sizing */
.cb-content math { font-size: 0.95em; }
.cb-content p { margin: 0 0 0.5em; }
.cb-content p:last-child { margin-bottom: 0; }

/* Knowledge state progression */
.ks-progression-wrapper {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.2rem;
  box-shadow: var(--card-shadow);
}
.ks-progression-wrapper h3 {
  text-align: center;
  margin-bottom: 0.3rem;
}
.ks-subtitle {
  text-align: center;
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.ks-turn-nav {
  display: flex;
  gap: 0.3rem;
  justify-content: center;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}
.ks-turn-btn {
  padding: 0.3rem 0.7rem;
  border: 1px solid var(--border);
  border-radius: 5px;
  background: var(--bg);
  cursor: pointer;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-muted);
  transition: all 0.15s;
}
.ks-turn-btn:hover { border-color: var(--accent); color: var(--accent-dark); }
.ks-turn-btn.active { background: var(--accent); color: #fff; border-color: var(--accent); }

.ks-grid-wrapper { overflow-x: auto; }

.ks-grid {
  display: grid;
  gap: 2px;
  font-size: 0.78rem;
  min-width: 500px;
}
.ks-row {
  display: contents;
}
.ks-cell {
  padding: 0.35rem 0.5rem;
  border-radius: 4px;
  text-align: center;
  font-weight: 500;
  transition: background 0.2s, color 0.2s;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.ks-cell.iu-label {
  text-align: left;
  font-weight: 600;
  color: var(--text);
  background: transparent;
  min-width: 180px;
  font-size: 0.76rem;
}
.ks-cell.header {
  font-weight: 700;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  color: var(--text-muted);
  background: transparent;
}
/* Knowledge state colors */
.ks-cell.unaware      { background: #f1f5f9; color: #94a3b8; }
.ks-cell.struggling    { background: #fee2e2; color: #991b1b; }
.ks-cell.partial       { background: #fef3c7; color: #92400e; }
.ks-cell.knows_well    { background: #d1fae5; color: #065f46; }
/* Highlight cells that changed */
.ks-cell.changed       { outline: 2px solid var(--accent); outline-offset: -1px; }

/* State legend */
.ks-legend {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin-top: 0.8rem;
  flex-wrap: wrap;
}
.ks-legend-item {
  display: flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 0.75rem;
  color: var(--text-muted);
}
.ks-legend-swatch {
  width: 14px;
  height: 14px;
  border-radius: 3px;
}

/* ========== Results ========== */
.tab-bar {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
  justify-content: center;
}
.tab-btn {
  padding: 0.4rem 1rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--bg);
  cursor: pointer;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
  transition: all 0.2s;
}
.tab-btn:hover { border-color: var(--accent); color: var(--accent-dark); }
.tab-btn.active { background: var(--accent); color: #fff; border-color: var(--accent); }

.result-panel { display: none; }
.result-panel.active { display: block; }

.chart-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}
.chart-container {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.2rem;
  box-shadow: var(--card-shadow);
}
.chart-container h3 { font-size: 0.95rem; text-align: center; margin-bottom: 0.8rem; }
.chart-container svg { width: 100%; height: auto; }

/* ========== Benchmarking Table ========== */
.table-wrapper {
  overflow-x: auto;
  margin-top: 1.5rem;
}
.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.82rem;
}
.data-table th, .data-table td {
  padding: 0.5rem 0.6rem;
  border: 1px solid var(--border);
  text-align: center;
}
.data-table th {
  background: var(--bg-alt);
  font-weight: 700;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  color: var(--text-muted);
}
.data-table .level-header {
  background: var(--accent-light);
  color: var(--accent-dark);
  font-size: 0.85rem;
}
.data-table td.model-name { text-align: left; font-weight: 600; }
.data-table td.best { font-weight: 700; color: var(--accent-dark); }
.data-table td.level-border { border-left: 2px solid #cbd5e1; }
.data-table tr:hover { background: #f8fafc; }

.table-level-tabs {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1rem;
  justify-content: center;
}

/* ========== Citation ========== */
.citation-block {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.2rem;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.78rem;
  line-height: 1.6;
  position: relative;
  white-space: pre-wrap;
  color: var(--text);
  max-width: 700px;
  margin: 1rem auto 0;
}
.copy-btn {
  position: absolute;
  top: 0.6rem;
  right: 0.6rem;
  padding: 0.3rem 0.6rem;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: var(--bg);
  cursor: pointer;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  transition: all 0.2s;
}
.copy-btn:hover { background: var(--accent-light); color: var(--accent-dark); }

/* ========== Footer ========== */
footer {
  padding: 2rem 0;
  border-top: 1px solid var(--border);
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-muted);
}
footer a { color: var(--accent-dark); }
footer .footer-links { display: flex; justify-content: center; gap: 1.5rem; margin-bottom: 0.5rem; }

/* ========== Responsive ========== */
@media (max-width: 768px) {
  .hero h1 { font-size: 1.6rem; }
  .side-by-side { grid-template-columns: 1fr; }
  .steps { grid-template-columns: 1fr; }
  .metric-cards { grid-template-columns: 1fr 1fr; }
  .chart-grid { grid-template-columns: 1fr; }
  .conv-comparison { grid-template-columns: 1fr; }
  .conv-scroll { max-height: 400px; }
  nav .nav-links { gap: 0.8rem; }
  nav .nav-links a { font-size: 0.78rem; }
}

@media (max-width: 480px) {
  .metric-cards { grid-template-columns: 1fr; }
  nav .nav-links { display: none; }
}

/* ========== Conversation insight ========== */
.conv-insight {
  margin-top: 2.5rem;
  padding: 1rem 1.2rem;
  background: #eff6ff;
  border-left: 3px solid var(--accent);
  border-radius: 0 6px 6px 0;
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--text);
}
.conv-insight h4 {
  font-family: 'Source Serif 4', Georgia, serif;
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--accent-dark);
  margin-bottom: 0.4rem;
}
.conv-insight p {
  margin: 0;
}
.conv-insight strong {
  color: var(--accent-dark);
}

/* ========== Same-assistant note ========== */
.same-assistant-note {
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
  background: var(--bg-alt);
  border: 1px dashed var(--border);
  border-radius: 6px;
  padding: 0.4rem 0.8rem;
  margin-bottom: 0.8rem;
}

/* ========== IU Graph ========== */
.iu-graph-wrapper {
  margin: 1.5rem 0;
  padding: 1.2rem 1.5rem;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
}
.iu-graph-wrapper h3 {
  font-size: 1rem;
  margin-bottom: 0.2rem;
}
.iu-graph-subtitle {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 0.8rem;
}
.iu-graph-container {
  overflow-x: auto;
  padding: 0.5rem 0;
}
.iu-graph-container svg {
  display: block;
  margin: 0 auto;
}