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

:root {
  --color-bg: #0f1117;
  --color-bg-alt: #161b27;
  --color-surface: #1e2535;
  --color-border: #2a3245;
  --color-accent: #5b8af0;
  --color-accent-hover: #7aa3ff;
  --color-accent-muted: rgba(91, 138, 240, 0.12);
  --color-text: #e2e8f0;
  --color-text-muted: #94a3b8;
  --color-text-faint: #64748b;
  --color-tag-bg: #1e2d4a;
  --color-tag-text: #93c5fd;

  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-serif: 'Merriweather', Georgia, serif;

  --nav-height: 64px;
  --section-padding: 96px;
  --container-max: 900px;
  --radius: 10px;
  --radius-sm: 6px;

  --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --transition: 0.2s ease;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

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

ul { list-style: none; }

img { max-width: 100%; display: block; }

/* =========================================
   Layout
   ========================================= */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
}

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

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

/* =========================================
   Navigation
   ========================================= */
#navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(15, 17, 23, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  z-index: 100;
  transition: box-shadow var(--transition);
}

#navbar.scrolled {
  box-shadow: var(--shadow);
}

.nav-inner {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.nav-logo {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-text);
  white-space: nowrap;
}
.nav-logo:hover { color: var(--color-accent); }

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-links a {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  font-weight: 500;
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  transition: color var(--transition), background var(--transition);
}
.nav-links a:hover,
.nav-links a.active {
  color: var(--color-text);
  background: var(--color-surface);
}

.btn-contact {
  color: var(--color-accent) !important;
  border: 1px solid var(--color-accent) !important;
  border-radius: var(--radius-sm) !important;
  padding: 6px 14px !important;
}
.btn-contact:hover {
  background: var(--color-accent-muted) !important;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--color-text);
  font-size: 1.4rem;
  cursor: pointer;
  padding: 4px;
}

/* =========================================
   Hero / About
   ========================================= */
.hero {
  padding-top: calc(var(--nav-height) + 80px);
  padding-bottom: 96px;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 48px;
  align-items: center;
}

.hero-greeting {
  font-size: 1rem;
  color: var(--color-accent);
  font-weight: 500;
  margin-bottom: 8px;
  letter-spacing: 0.05em;
}

.hero-name {
  font-size: clamp(2.2rem, 5vw, 3.2rem);
  font-weight: 700;
  line-height: 1.15;
  margin-bottom: 8px;
  letter-spacing: -0.02em;
}

.hero-title {
  font-size: 1.15rem;
  font-weight: 400;
  color: var(--color-text-muted);
  margin-bottom: 20px;
}

.hero-bio {
  color: var(--color-text-muted);
  max-width: 540px;
  margin-bottom: 28px;
  font-size: 0.975rem;
  line-height: 1.75;
}

.hero-links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.pill {
  display: inline-block;
  padding: 7px 16px;
  border-radius: 999px;
  border: 1px solid var(--color-border);
  color: var(--color-text-muted);
  font-size: 0.85rem;
  font-weight: 500;
  transition: all var(--transition);
}
.pill:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  background: var(--color-accent-muted);
}

.pill-accent {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: #fff !important;
}
.pill-accent:hover {
  background: var(--color-accent-hover);
  border-color: var(--color-accent-hover);
  color: #fff !important;
}

.hero-photo {
  flex-shrink: 0;
}

.hero-photo img,
.photo-placeholder {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid var(--color-border);
  box-shadow: var(--shadow);
}

.photo-placeholder {
  display: none;
  align-items: center;
  justify-content: center;
  background: var(--color-surface);
  color: var(--color-text-faint);
  font-size: 0.85rem;
}

/* =========================================
   Section Titles
   ========================================= */
.section-title {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 8px;
  letter-spacing: -0.02em;
  position: relative;
  padding-bottom: 16px;
}

.section-title::after {
  content: '';
  display: block;
  position: absolute;
  bottom: 0;
  left: 0;
  width: 40px;
  height: 3px;
  background: var(--color-accent);
  border-radius: 2px;
}

.section-subtitle {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  margin-top: 4px;
  margin-bottom: 36px;
}

/* =========================================
   Tabs
   ========================================= */
.tab-bar {
  display: flex;
  gap: 4px;
  margin: 28px 0 32px;
  border-bottom: 1px solid var(--color-border);
  padding-bottom: 0;
}

.tab-btn {
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  color: var(--color-text-muted);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 500;
  padding: 8px 20px;
  cursor: pointer;
  margin-bottom: -1px;
  transition: all var(--transition);
}

.tab-btn:hover {
  color: var(--color-text);
}

.tab-btn.active {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

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

/* =========================================
   Timeline
   ========================================= */
.timeline {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.timeline-item {
  display: grid;
  grid-template-columns: 20px 1fr;
  gap: 0 20px;
  position: relative;
  padding-bottom: 36px;
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-item:not(:last-child) .timeline-dot::after {
  content: '';
  display: block;
  position: absolute;
  top: 20px;
  left: 9px;
  width: 2px;
  height: calc(100% - 20px);
  background: var(--color-border);
}

.timeline-dot {
  position: relative;
  margin-top: 4px;
}

.timeline-dot::before {
  content: '';
  display: block;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--color-accent);
  border: 2px solid var(--color-bg);
  box-shadow: 0 0 0 2px var(--color-accent);
  margin-top: 4px;
}

.timeline-content {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px 24px;
}

.timeline-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 12px;
  margin-bottom: 12px;
}

.job-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text);
}

.org-name {
  font-size: 0.9rem;
  color: var(--color-accent);
  margin-top: 2px;
}

.timeline-date {
  font-size: 0.82rem;
  color: var(--color-text-faint);
  white-space: nowrap;
  flex-shrink: 0;
  margin-top: 2px;
}

.bullet-list {
  list-style: disc;
  padding-left: 18px;
  color: var(--color-text-muted);
  font-size: 0.9rem;
  margin-bottom: 14px;
}

.bullet-list li {
  margin-bottom: 4px;
}

/* =========================================
   Tags
   ========================================= */
.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.tag {
  display: inline-block;
  padding: 3px 10px;
  background: var(--color-tag-bg);
  color: var(--color-tag-text);
  border-radius: 4px;
  font-size: 0.78rem;
  font-weight: 500;
}

/* =========================================
   Project Cards
   ========================================= */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 20px;
  margin-top: 36px;
}

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: border-color var(--transition), transform var(--transition), box-shadow var(--transition);
}

.card:hover {
  border-color: var(--color-accent);
  transform: translateY(-3px);
  box-shadow: var(--shadow);
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 12px;
}

.card-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text);
}

.card-links {
  display: flex;
  gap: 8px;
  flex-shrink: 0;
}

.icon-link {
  color: var(--color-text-faint);
  transition: color var(--transition);
}
.icon-link:hover { color: var(--color-accent); }

.card-description {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  line-height: 1.65;
  flex: 1;
}

/* =========================================
   Publications
   ========================================= */
.pub-list {
  display: flex;
  flex-direction: column;
  gap: 0;
  margin-top: 36px;
}

.pub-item {
  display: grid;
  grid-template-columns: 60px 1fr;
  gap: 16px 24px;
  padding: 24px 0;
  border-bottom: 1px solid var(--color-border);
}

.pub-item:last-child {
  border-bottom: none;
}

.pub-year {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--color-accent);
  margin-top: 3px;
  text-align: right;
  letter-spacing: 0.03em;
}

.pub-title {
  font-size: 0.975rem;
  font-weight: 600;
  margin-bottom: 4px;
  line-height: 1.5;
}

.pub-title a {
  color: var(--color-text);
}
.pub-title a:hover { color: var(--color-accent); }

.pub-authors {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-bottom: 2px;
}

.pub-venue {
  font-size: 0.875rem;
  color: var(--color-text-faint);
  margin-bottom: 10px;
}

.pub-links {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.pub-link {
  font-size: 0.78rem;
  font-weight: 500;
  padding: 3px 10px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
  transition: all var(--transition);
}
.pub-link:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  background: var(--color-accent-muted);
}

/* =========================================
   Awards
   ========================================= */
.awards-grid {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-top: 36px;
}

.award-item {
  display: flex;
  gap: 20px;
  align-items: flex-start;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px 24px;
  transition: border-color var(--transition);
}

.award-item:hover {
  border-color: var(--color-accent);
}

.award-icon {
  font-size: 1.6rem;
  flex-shrink: 0;
  line-height: 1;
  margin-top: 2px;
}

.award-title {
  font-size: 0.975rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.award-org {
  font-size: 0.85rem;
  color: var(--color-accent);
  margin-bottom: 6px;
}

.award-desc {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

/* =========================================
   Footer
   ========================================= */
.footer {
  border-top: 1px solid var(--color-border);
  padding: 32px 0;
  text-align: center;
  color: var(--color-text-faint);
  font-size: 0.85rem;
}

.footer a {
  color: var(--color-text-faint);
}
.footer a:hover { color: var(--color-accent); }

.footer-note {
  margin-top: 4px;
}

/* =========================================
   Responsive
   ========================================= */
@media (max-width: 700px) {
  :root {
    --section-padding: 64px;
  }

  .nav-toggle { display: block; }

  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--color-bg-alt);
    border-bottom: 1px solid var(--color-border);
    flex-direction: column;
    align-items: stretch;
    padding: 8px 16px 16px;
    gap: 2px;
  }

  .nav-links.open { display: flex; }

  .nav-links a {
    padding: 10px 12px;
    font-size: 0.95rem;
  }

  .hero-grid {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .hero-photo {
    order: -1;
    display: flex;
    justify-content: center;
  }

  .hero-photo img,
  .photo-placeholder {
    width: 160px;
    height: 160px;
  }

  .hero-bio { margin: 0 auto 28px; }

  .hero-links { justify-content: center; }

  .section-title::after { left: 50%; transform: translateX(-50%); }
  .section-title { text-align: center; }
  .section-subtitle { text-align: center; }

  .timeline-item {
    grid-template-columns: 1fr;
  }
  .timeline-dot { display: none; }

  .timeline-header {
    flex-direction: column;
    gap: 4px;
  }

  .pub-item {
    grid-template-columns: 1fr;
    gap: 6px;
  }

  .pub-year { text-align: left; }

  .card-grid { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .hero-photo img,
  .photo-placeholder {
    width: 130px;
    height: 130px;
  }
}