/* ═══════════════════════════════════════════════════════════════
 *  RONGBING XU — Academic Homepage Stylesheet
 *  Aesthetic: Editorial Precision × Aviation Instrument
 * ═══════════════════════════════════════════════════════════════ */

/* ── CSS Custom Properties ──────────────────────────────────── */
:root {
  /* Typography */
  --font-display: 'DM Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-body: 'DM Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  /* Type Scale (Major Third 1.25) */
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;
  --text-5xl: 3rem;
  --text-6xl: 3.75rem;

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Dimensions */
  --container-max: 1120px;
  --nav-height: 64px;
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-full: 9999px;

  /* Transitions */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-in-out: cubic-bezier(0.65, 0, 0.35, 1);
  --duration-fast: 150ms;
  --duration-base: 250ms;
  --duration-slow: 400ms;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.06);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.08);
  --shadow-xl: 0 16px 48px rgba(0,0,0,0.1);
}

/* ── Light Theme ────────────────────────────────────────────── */
[data-theme="light"] {
  --bg-primary: #FAFBFD;
  --bg-secondary: #F0F2F7;
  --bg-card: #FFFFFF;
  --bg-card-hover: #F8FAFC;
  --bg-nav: rgba(250, 251, 253, 0.88);

  --text-primary: #1A1D24;
  --text-secondary: #454B58;
  --text-tertiary: #717889;
  --text-inverse: #FAFBFD;

  --accent: #2B5EA7;
  --accent-hover: #1E4A8A;
  --accent-light: #E8F0FA;
  --accent-subtle: rgba(43, 94, 167, 0.08);

  --border: #DCE1EA;
  --border-light: #E8ECF3;
  --border-accent: rgba(43, 94, 167, 0.25);

  --status-published: #1A7A4C;
  --status-accepted: #2563AA;
  --status-review: #B8860B;
  --status-other: #6B6B75;

  --tag-bg: #ECF0F7;
  --tag-text: #4A5268;

  --scrollbar-track: #ECF0F7;
  --scrollbar-thumb: #C4CADA;
}

/* ── Dark Theme ─────────────────────────────────────────────── */
[data-theme="dark"] {
  --bg-primary: #0F1318;
  --bg-secondary: #161C26;
  --bg-card: #181D26;
  --bg-card-hover: #1E2530;
  --bg-nav: rgba(15, 19, 24, 0.92);

  --text-primary: #E2E6ED;
  --text-secondary: #9AA3B4;
  --text-tertiary: #6A7385;
  --text-inverse: #0F1318;

  --accent: #5B9CF5;
  --accent-hover: #7BB3FF;
  --accent-light: #1A2540;
  --accent-subtle: rgba(91, 156, 245, 0.1);

  --border: #242C3B;
  --border-light: #1D2433;
  --border-accent: rgba(91, 156, 245, 0.3);

  --status-published: #34D399;
  --status-accepted: #60A5FA;
  --status-review: #FBBF24;
  --status-other: #9CA3AF;

  --tag-bg: #1E2636;
  --tag-text: #9CA3AF;

  --scrollbar-track: #151B27;
  --scrollbar-thumb: #2A3448;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.2);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.25);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.35);
  --shadow-xl: 0 16px 48px rgba(0,0,0,0.4);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-height) + var(--space-8));
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.7;
  color: var(--text-primary);
  background: var(--bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background var(--duration-slow) var(--ease-out),
              color var(--duration-slow) var(--ease-out);
  overflow-x: hidden;
}

/* Scrollbar */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: var(--scrollbar-track); }
::-webkit-scrollbar-thumb { background: var(--scrollbar-thumb); border-radius: var(--radius-full); }

a {
  color: var(--accent);
  text-decoration: none;
  transition: color var(--duration-fast);
}
a:hover { color: var(--accent-hover); }
a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 2px;
}

img { max-width: 100%; height: auto; display: block; }
button { cursor: pointer; border: none; background: none; font-family: inherit; }
input { font-family: inherit; }

::selection {
  background: var(--accent);
  color: var(--text-inverse);
}

.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

/* ── Navigation ─────────────────────────────────────────────── */
.nav-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--nav-height);
  background: var(--bg-nav);
  backdrop-filter: blur(16px) saturate(1.4);
  -webkit-backdrop-filter: blur(16px) saturate(1.4);
  border-bottom: 1px solid var(--border-light);
  transition: background var(--duration-slow) var(--ease-out),
              border-color var(--duration-slow) var(--ease-out),
              box-shadow var(--duration-base) var(--ease-out);
}

.nav-header.scrolled {
  box-shadow: var(--shadow-sm);
}

.nav-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-6);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-8);
}

.nav-logo {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  color: var(--text-primary);
  letter-spacing: -0.02em;
  text-decoration: none;
  flex-shrink: 0;
}
.nav-logo:hover { color: var(--accent); }
.nav-logo-dot { color: var(--accent); }

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.nav-link {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--text-secondary);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-sm);
  transition: color var(--duration-fast), background var(--duration-fast);
  white-space: nowrap;
}
.nav-link:hover {
  color: var(--text-primary);
  background: var(--accent-subtle);
}
.nav-link.active {
  color: var(--accent);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

/* Language Toggle */
.lang-toggle {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-size: var(--text-sm);
  font-weight: 600;
  transition: color var(--duration-fast), background var(--duration-fast);
}
.lang-toggle:hover {
  color: var(--accent);
  background: var(--accent-subtle);
}

/* Theme Toggle */
.theme-toggle {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  transition: color var(--duration-fast), background var(--duration-fast);
}
.theme-toggle:hover {
  color: var(--accent);
  background: var(--accent-subtle);
}
[data-theme="light"] .icon-moon { display: none; }
[data-theme="dark"] .icon-sun { display: none; }

/* Hamburger */
.nav-hamburger {
  display: none;
  width: 36px;
  height: 36px;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  border-radius: var(--radius-md);
}
.nav-hamburger span {
  display: block;
  width: 18px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 1px;
  transition: transform var(--duration-base) var(--ease-out),
              opacity var(--duration-fast);
}
.nav-hamburger[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav-hamburger[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}
.nav-hamburger[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ── Hero ────────────────────────────────────────────────────── */
.hero {
  padding-top: calc(var(--nav-height) + var(--space-16));
  padding-bottom: var(--space-16);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background:
    radial-gradient(ellipse 60% 50% at 70% 20%, var(--accent-subtle), transparent),
    radial-gradient(ellipse 40% 40% at 20% 80%, var(--accent-subtle), transparent);
  pointer-events: none;
}

.hero-grid {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: var(--space-12);
  align-items: start;
  position: relative;
}

.hero-photo {
  width: 200px;
  height: 200px;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 3px solid var(--border);
  box-shadow: var(--shadow-lg);
  background: var(--bg-secondary);
  position: relative;
}

.hero-photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.hero-photo-placeholder {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-size: var(--text-4xl);
  color: var(--text-tertiary);
  background: linear-gradient(145deg, var(--bg-secondary), var(--bg-card));
}

.hero-name {
  font-family: var(--font-display);
  font-size: var(--text-5xl);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.03em;
  color: var(--text-primary);
  margin-bottom: var(--space-3);
}

.hero-titles {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  margin-bottom: var(--space-6);
}

.hero-title-line {
  font-size: var(--text-lg);
  color: var(--text-secondary);
  font-weight: 400;
}
.hero-title-line .hl {
  color: var(--accent);
  font-weight: 500;
}
.hero-org-link {
  color: var(--accent);
  font-weight: 500;
  text-decoration: none;
}
.hero-org-link:hover {
  color: var(--accent-hover);
}

.hero-tagline {
  font-size: var(--text-lg);
  color: var(--text-tertiary);
  font-weight: 400;
  max-width: 600px;
  margin-bottom: var(--space-8);
  line-height: 1.7;
}

/* Metrics bar */
.hero-metrics {
  display: flex;
  gap: var(--space-4);
  margin-bottom: var(--space-8);
  flex-wrap: wrap;
}

.metric-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-4) var(--space-5);
  min-width: 110px;
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: border-color var(--duration-fast), box-shadow var(--duration-fast);
}
.metric-card:hover {
  border-color: var(--border-accent);
  box-shadow: var(--shadow-md);
}

.metric-value {
  font-family: var(--font-mono);
  font-size: var(--text-2xl);
  font-weight: 500;
  color: var(--accent);
  line-height: 1.2;
}

.metric-label {
  font-size: var(--text-xs);
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-top: var(--space-1);
}

/* CTA buttons */
.hero-cta {
  display: flex;
  gap: var(--space-3);
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-5);
  font-size: var(--text-sm);
  font-weight: 600;
  border-radius: var(--radius-md);
  transition: all var(--duration-fast);
  white-space: nowrap;
}

.btn-primary {
  background: var(--accent);
  color: var(--text-inverse);
}
.btn-primary:hover {
  background: var(--accent-hover);
  color: var(--text-inverse);
  box-shadow: var(--shadow-md);
}

.btn-outline {
  border: 1.5px solid var(--border);
  color: var(--text-secondary);
  background: var(--bg-card);
}
.btn-outline:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-subtle);
}

.btn svg {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
}

/* ── Section Common ──────────────────────────────────────────── */
.section {
  padding: var(--space-20) 0;
}

.section-alt {
  background: var(--bg-secondary);
}

.section-title {
  font-family: var(--font-display);
  font-size: var(--text-3xl);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-10);
  display: flex;
  align-items: center;
  gap: var(--space-5);
  letter-spacing: -0.02em;
}

.section-title::after {
  content: '';
  flex: 1;
  height: 1px;
  background: linear-gradient(90deg, var(--border), transparent);
}

/* ── About ───────────────────────────────────────────────────── */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: var(--space-12);
  align-items: start;
}

.about-bio {
  font-size: var(--text-base);
  line-height: 1.8;
  color: var(--text-secondary);
}
.about-bio strong { color: var(--text-primary); font-weight: 600; }
.about-bio a { text-decoration: underline; text-underline-offset: 3px; }

.sidebar-title {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-2);
  border-bottom: 1px solid var(--border);
}

.news-item {
  padding: var(--space-3) 0;
  border-bottom: 1px solid var(--border-light);
  display: flex;
  gap: var(--space-3);
  font-size: var(--text-sm);
}
.news-item:last-child { border-bottom: none; }

.news-date {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--accent);
  flex-shrink: 0;
  min-width: 44px;
  padding-top: 2px;
}

.news-text {
  color: var(--text-secondary);
  line-height: 1.6;
}
.news-text strong { color: var(--text-primary); }

/* ── Research Interests ──────────────────────────────────────── */
.research-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-6);
}

.research-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-6);
  transition: border-color var(--duration-fast), box-shadow var(--duration-fast),
              transform var(--duration-base) var(--ease-out);
}
.research-card:hover {
  border-color: var(--border-accent);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.research-icon {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-light);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-4);
  color: var(--accent);
}

.research-card h3 {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}

.research-card p {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ── Publications ────────────────────────────────────────────── */
.pub-controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  margin-bottom: var(--space-8);
  flex-wrap: wrap;
}

.pub-filters {
  display: flex;
  gap: var(--space-1);
  flex-wrap: wrap;
}

.pub-filter-btn {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--text-tertiary);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-full);
  border: 1px solid transparent;
  transition: all var(--duration-fast);
  white-space: nowrap;
}
.pub-filter-btn:hover {
  color: var(--text-primary);
  background: var(--accent-subtle);
}
.pub-filter-btn.active {
  color: var(--accent);
  background: var(--accent-light);
  border-color: var(--border-accent);
}

.pub-search-wrap {
  position: relative;
  max-width: 280px;
  flex-shrink: 0;
}
.pub-search-icon {
  position: absolute;
  left: var(--space-3);
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-tertiary);
  pointer-events: none;
}
.pub-search {
  width: 100%;
  padding: var(--space-2) var(--space-4) var(--space-2) var(--space-10);
  font-size: var(--text-sm);
  color: var(--text-primary);
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  outline: none;
  transition: border-color var(--duration-fast), box-shadow var(--duration-fast);
}
.pub-search:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-subtle);
}
.pub-search::placeholder { color: var(--text-tertiary); }

/* Publication List */
.pub-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.pub-year-group h3 {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-2);
  border-bottom: 1px solid var(--border-light);
}

.pub-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-left: 3px solid var(--status-published);
  border-radius: var(--radius-md);
  padding: var(--space-5) var(--space-6);
  transition: border-color var(--duration-fast), box-shadow var(--duration-fast),
              transform var(--duration-base) var(--ease-out);
}
.pub-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}
.pub-card[data-status="accepted"] { border-left-color: var(--status-accepted); }
.pub-card[data-status="under_review"] { border-left-color: var(--status-review); }
.pub-card[data-status="other"] { border-left-color: var(--status-other); }

.pub-title {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 500;
  color: var(--text-primary);
  line-height: 1.4;
  margin-bottom: var(--space-2);
}

.pub-authors {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  margin-bottom: var(--space-2);
  line-height: 1.6;
}
.pub-authors .author-highlight {
  font-weight: 600;
  color: var(--text-primary);
}

.pub-meta {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  flex-wrap: wrap;
  font-size: var(--text-sm);
}

.pub-venue {
  font-style: italic;
  color: var(--text-tertiary);
}

.pub-badge {
  font-size: var(--text-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 2px var(--space-2);
  border-radius: var(--radius-sm);
}
.pub-badge.published { background: rgba(26,122,76,0.1); color: var(--status-published); }
.pub-badge.accepted { background: rgba(37,99,170,0.1); color: var(--status-accepted); }
.pub-badge.under_review { background: rgba(184,134,11,0.1); color: var(--status-review); }
.pub-badge.other { background: rgba(107,107,117,0.1); color: var(--status-other); }

[data-theme="dark"] .pub-badge.published { background: rgba(52,211,153,0.12); }
[data-theme="dark"] .pub-badge.accepted { background: rgba(96,165,250,0.12); }
[data-theme="dark"] .pub-badge.under_review { background: rgba(251,191,36,0.12); }
[data-theme="dark"] .pub-badge.other { background: rgba(156,163,175,0.12); }

.pub-type-badge {
  font-size: var(--text-xs);
  color: var(--text-tertiary);
  border: 1px solid var(--border);
  padding: 1px var(--space-2);
  border-radius: var(--radius-sm);
}

.pub-links {
  display: flex;
  gap: var(--space-2);
  margin-top: var(--space-3);
}

.pub-link {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--accent);
  padding: var(--space-1) var(--space-3);
  border: 1px solid var(--border-accent);
  border-radius: var(--radius-sm);
  transition: all var(--duration-fast);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.pub-link:hover {
  background: var(--accent);
  color: var(--text-inverse);
}

.pub-tags {
  display: flex;
  gap: var(--space-2);
  margin-top: var(--space-3);
  flex-wrap: wrap;
}

.pub-tag {
  font-size: var(--text-xs);
  color: var(--tag-text);
  background: var(--tag-bg);
  padding: 1px var(--space-2);
  border-radius: var(--radius-sm);
}

.pub-empty {
  text-align: center;
  color: var(--text-tertiary);
  padding: var(--space-12) 0;
  font-style: italic;
}

/* Publication Pagination */
.pub-pagination {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-4);
  margin-top: var(--space-8);
  padding-top: var(--space-6);
  border-top: 1px solid var(--border-light);
}

.pub-page-btn {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--accent);
  padding: var(--space-2) var(--space-5);
  border: 1.5px solid var(--border-accent);
  border-radius: var(--radius-md);
  background: var(--bg-card);
  transition: all var(--duration-fast);
}
.pub-page-btn:hover:not(:disabled) {
  background: var(--accent);
  color: var(--text-inverse);
}
.pub-page-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.pub-page-info {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--text-tertiary);
}

.pub-first-author-marker,
.pub-corresponding-marker {
  display: inline-block;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  margin-left: var(--space-2);
  vertical-align: middle;
}

.pub-first-author-marker {
  background: var(--accent);
}

.pub-corresponding-marker {
  background: var(--status-accepted);
}

/* ── Timeline (Experience & Education) ───────────────────────── */
.timeline {
  position: relative;
  padding-left: var(--space-8);
}

.timeline::before {
  content: '';
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: linear-gradient(180deg, var(--accent), var(--border));
  border-radius: 1px;
}

.timeline-item {
  position: relative;
  padding-bottom: var(--space-10);
}
.timeline-item:last-child { padding-bottom: 0; }

.timeline-item::before {
  content: '';
  position: absolute;
  left: calc(-1 * var(--space-8) + 3px);
  top: 8px;
  width: 10px;
  height: 10px;
  background: var(--bg-primary);
  border: 2px solid var(--accent);
  border-radius: 50%;
  z-index: 1;
}

.section-alt .timeline-item::before {
  background: var(--bg-secondary);
}

.timeline-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-4);
  margin-bottom: var(--space-1);
  flex-wrap: wrap;
}

.timeline-org {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 600;
  color: var(--text-primary);
}

.timeline-period {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--accent);
  white-space: nowrap;
}

.timeline-role {
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: var(--space-1);
}

.timeline-location {
  font-size: var(--text-sm);
  color: var(--text-tertiary);
  margin-bottom: var(--space-3);
}

.timeline-details {
  list-style: none;
}

.timeline-details li {
  position: relative;
  padding-left: var(--space-5);
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-2);
}

.timeline-details li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 10px;
  width: 5px;
  height: 1px;
  background: var(--accent);
}

/* ── Teaching ────────────────────────────────────────────────── */
.teaching-table-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.teaching-table {
  width: 100%;
  border-collapse: collapse;
}

.teaching-table th {
  text-align: left;
  font-size: var(--text-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-tertiary);
  padding: var(--space-3) var(--space-4);
  border-bottom: 2px solid var(--border);
}

.teaching-table td {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  padding: var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--border-light);
}

.teaching-table tr:hover td {
  background: var(--accent-subtle);
}

.teaching-table .course-name {
  font-weight: 600;
  color: var(--text-primary);
}

.teaching-table .term-col {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--accent);
  white-space: nowrap;
}

/* ── Awards ──────────────────────────────────────────────────── */
.awards-grid {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.award-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-5) var(--space-6);
  display: flex;
  align-items: flex-start;
  gap: var(--space-5);
  transition: border-color var(--duration-fast), box-shadow var(--duration-fast);
}
.award-card:hover {
  border-color: var(--border-accent);
  box-shadow: var(--shadow-sm);
}

.award-year {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--accent);
  flex-shrink: 0;
  min-width: 100px;
}

.award-content h3 {
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-1);
}

.award-content p {
  font-size: var(--text-sm);
  color: var(--text-secondary);
}

/* ── Service ─────────────────────────────────────────────────── */
.service-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-6);
}

.service-section {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-6);
}

.service-section h3 {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-2);
  border-bottom: 1px solid var(--border-light);
}

.service-list {
  list-style: none;
}

.service-list li {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  padding: var(--space-2) 0;
  border-bottom: 1px solid var(--border-light);
  line-height: 1.6;
}
.service-list li:last-child { border-bottom: none; }

.service-role {
  font-weight: 600;
  color: var(--text-primary);
  display: block;
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 2px;
}

/* ── Contact ─────────────────────────────────────────────────── */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-8);
  max-width: 700px;
}

.contact-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-4);
}

.contact-icon {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-light);
  border-radius: var(--radius-md);
  color: var(--accent);
  flex-shrink: 0;
}

.contact-label {
  font-size: var(--text-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-tertiary);
  margin-bottom: var(--space-1);
}

.contact-value {
  font-size: var(--text-sm);
  color: var(--text-primary);
  word-break: break-word;
}
.contact-value a {
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ── Footer ──────────────────────────────────────────────────── */
.footer {
  border-top: 1px solid var(--border);
  padding: var(--space-8) 0;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer-copy, .footer-update {
  font-size: var(--text-sm);
  color: var(--text-tertiary);
}

/* ── Back to Top ─────────────────────────────────────────────── */
.back-to-top {
  position: fixed;
  bottom: var(--space-6);
  right: var(--space-6);
  width: 42px;
  height: 42px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  color: var(--text-secondary);
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity var(--duration-base), visibility var(--duration-base),
              transform var(--duration-base) var(--ease-out),
              color var(--duration-fast), border-color var(--duration-fast);
  z-index: 50;
}
.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.back-to-top:hover {
  color: var(--accent);
  border-color: var(--accent);
}

/* ── Section Collapsible ──────────────────────────────────────── */
.section-collapsible {
  max-height: var(--collapse-height, 350px);
  overflow: hidden;
  position: relative;
  transition: max-height 0.5s cubic-bezier(0.16, 1, 0.3, 1);
}

.section-collapsible::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 80px;
  background: linear-gradient(to bottom, transparent, var(--bg-primary));
  pointer-events: none;
  z-index: 1;
  transition: opacity var(--duration-base);
}

.section-alt .section-collapsible::after {
  background: linear-gradient(to bottom, transparent, var(--bg-secondary));
}

.section-collapsible.expanded {
  max-height: 5000px;
}

.section-collapsible.expanded::after {
  opacity: 0;
}

.section-toggle-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  margin: var(--space-6) auto 0;
  padding: var(--space-2) var(--space-6);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--accent);
  border: 1.5px solid var(--border-accent);
  border-radius: var(--radius-full);
  background: var(--bg-card);
  transition: all var(--duration-fast);
  z-index: 2;
  position: relative;
}
.section-toggle-btn:hover {
  background: var(--accent);
  color: var(--text-inverse);
}

.section-toggle-btn svg {
  transition: transform var(--duration-base) var(--ease-out);
}
.section-toggle-btn.expanded svg {
  transform: rotate(180deg);
}

/* ── Scroll Reveal Animation ─────────────────────────────────── */
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s var(--ease-out), transform 0.6s var(--ease-out);
}
.reveal.revealed {
  opacity: 1;
  transform: translateY(0);
}

.reveal-delay-1 { transition-delay: 0.08s; }
.reveal-delay-2 { transition-delay: 0.16s; }
.reveal-delay-3 { transition-delay: 0.24s; }
.reveal-delay-4 { transition-delay: 0.32s; }

/* ── Responsive ──────────────────────────────────────────────── */
@media (max-width: 1024px) {
  .about-grid {
    grid-template-columns: 1fr;
  }
  .service-grid {
    grid-template-columns: 1fr 1fr;
  }
  .research-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  :root {
    --text-5xl: 2.25rem;
    --text-4xl: 1.875rem;
    --text-3xl: 1.5rem;
  }

  .nav-links {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--bg-nav);
    backdrop-filter: blur(16px) saturate(1.4);
    -webkit-backdrop-filter: blur(16px) saturate(1.4);
    flex-direction: column;
    padding: var(--space-4) var(--space-6);
    border-bottom: 1px solid var(--border);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: transform var(--duration-base) var(--ease-out),
                opacity var(--duration-base),
                visibility var(--duration-base);
  }
  .nav-links.open {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }
  .nav-link {
    padding: var(--space-3) var(--space-4);
    width: 100%;
    font-size: var(--text-base);
  }

  .nav-hamburger { display: flex; }

  .hero {
    padding-top: calc(var(--nav-height) + var(--space-10));
    padding-bottom: var(--space-10);
  }
  .hero-grid {
    grid-template-columns: 1fr;
    gap: var(--space-8);
  }
  .hero-photo {
    width: 140px;
    height: 140px;
    margin: 0 auto;
  }
  .hero-content { text-align: center; }
  .hero-name { font-size: var(--text-4xl); }
  .hero-titles { align-items: center; }
  .hero-tagline { margin-left: auto; margin-right: auto; }
  .hero-metrics { justify-content: center; }
  .hero-cta { justify-content: center; }

  .section { padding: var(--space-12) 0; }

  .research-grid { grid-template-columns: 1fr; }
  .service-grid { grid-template-columns: 1fr; }
  .contact-grid { grid-template-columns: 1fr; }

  .pub-controls { flex-direction: column; align-items: stretch; }
  .pub-search-wrap { max-width: none; }

  .timeline { padding-left: var(--space-6); }
  .timeline-header { flex-direction: column; gap: 0; }

  .award-card { flex-direction: column; gap: var(--space-2); }

  .footer-inner { flex-direction: column; gap: var(--space-2); text-align: center; }
}

@media (max-width: 480px) {
  .container { padding: 0 var(--space-4); }
  .hero-metrics { flex-direction: column; align-items: center; }
  .metric-card { width: 100%; max-width: 200px; }
  .hero-cta { flex-direction: column; align-items: center; }
  .btn { width: 100%; max-width: 280px; justify-content: center; }
}

/* ── Print Styles ────────────────────────────────────────────── */
@media print {
  *,
  *::before,
  *::after {
    background: transparent !important;
    color: #000 !important;
    box-shadow: none !important;
    text-shadow: none !important;
  }

  body { font-size: 11pt; line-height: 1.5; }

  .nav-header,
  .theme-toggle,
  .nav-hamburger,
  .back-to-top,
  .pub-controls,
  .hero-cta { display: none !important; }

  .hero { padding-top: 0; }
  .hero::before { display: none; }
  .section { padding: 16pt 0; }
  .container { max-width: none; padding: 0; }

  a[href]::after { content: " (" attr(href) ")"; font-size: 9pt; color: #666; }
  a[href^="#"]::after,
  a[href^="javascript"]::after { content: ""; }

  .pub-card { break-inside: avoid; border-left-width: 2px !important; }
  .timeline-item { break-inside: avoid; }
  .reveal { opacity: 1 !important; transform: none !important; }

  .hero-photo { width: 100px; height: 100px; }
}