:root {
  --bg-body: #050d1f;
  --bg-surface: #0e172b;
  --bg-surface-alt: #101d33;
  --bg-card: #16233b;
  --color-text: #e9edf5;
  --color-muted: rgba(233, 237, 245, 0.72);
  --color-accent: #20a4a6;
  --color-accent-soft: #2cc5c7;
  --color-border: rgba(255, 255, 255, 0.08);
  --shadow-soft: 0 18px 48px rgba(5, 12, 28, 0.45);
  --font-base: 'Merriweather', 'Georgia', 'Times New Roman', serif;
  --font-heading: 'Merriweather', 'Georgia', 'Times New Roman', serif;
}

* {
  box-sizing: border-box;
}

body {
  font-family: var(--font-base);
  background: var(--bg-body);
  color: var(--color-text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img {
  max-width: 100%;
  height: auto;
}

::selection {
  background: rgba(32, 164, 166, 0.35);
  color: #fff;
}

a {
  color: var(--color-accent);
}

a:hover,
a:focus {
  color: var(--color-accent-soft);
  text-decoration: none;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: var(--font-heading);
  line-height: 1.2;
  color: #fff;
}

.section {
  padding: 5rem 0;
}

.section-dark {
  background: var(--bg-surface);
}

.section-deep {
  background: var(--bg-body);
}

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

.section + .section {
  border-top: 1px solid rgba(255, 255, 255, 0.04);
}

.section-title {
  font-size: 2.5rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.section-subtitle {
  color: var(--color-muted);
  max-width: 640px;
  margin: 0 auto 2rem;
  font-size: 1.05rem;
}

.section-divider {
  width: 6rem;
  height: 3px;
  background: var(--color-accent);
  border-radius: 999px;
  margin: 1.25rem auto 0;
}

/* Navigation */
#mainNav {
  padding: 0.85rem 0;
  transition: background 0.35s ease, box-shadow 0.35s ease;
  background: rgba(6, 13, 31, 0.82);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}

#mainNav .navbar-brand {
  font-family: var(--font-heading);
  font-weight: 600;
  letter-spacing: 0.01em;
  color: #fff;
  display: flex;
  align-items: center;
}

#mainNav .navbar-brand:hover,
#mainNav .navbar-brand:focus {
  color: #fff;
}

#mainNav .brand-mark {
  width: 48px;
  height: auto;
  margin-right: 0.75rem;
  filter: drop-shadow(0 8px 16px rgba(0, 0, 0, 0.45));
}

.navbar-dark .navbar-toggler {
  border: none;
  font-size: 1.1rem;
  color: #fff;
}

.navbar-dark .navbar-nav .nav-link {
  color: rgba(255, 255, 255, 0.75);
  font-weight: 500;
  letter-spacing: 0.02em;
  padding: 0.5rem 0;
  margin-left: 1.5rem;
}

.navbar-dark .navbar-nav .nav-link:hover,
.navbar-dark .navbar-nav .nav-link:focus,
.navbar-dark .navbar-nav .nav-link.active {
  color: #fff;
}

.navbar-scrolled {
  background: rgba(6, 13, 31, 0.95) !important;
  box-shadow: 0 20px 40px rgba(3, 8, 20, 0.45);
}

/* Hero */
.hero-section {
  padding: 9rem 0 5rem;
  background: radial-gradient(86% 120% at 0% 0%, #16233b 0%, #0c1527 55%, #050d1f 100%);
}

.hero-section.hero-sub {
  padding: 8rem 0 4rem;
  background: radial-gradient(100% 140% at 20% 0%, #16233b 0%, #0a1426 65%, #050d1f 100%);
}

.hero-section.hero-sub .hero-title {
  font-size: 2.75rem;
}

.hero-title {
  font-size: 3rem;
  font-weight: 600;
  margin-bottom: 1.25rem;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  text-transform: uppercase;
  font-size: 0.85rem;
  letter-spacing: 0.2em;
  color: var(--color-accent-soft);
  margin-bottom: 1rem;
}

.hero-lead {
  color: var(--color-muted);
  font-size: 1.05rem;
  margin-bottom: 1.5rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  margin-bottom: 2rem;
}

.theme-tabs {
  background: rgba(6, 16, 32, 0.55);
  border: 1px solid var(--color-border);
  border-radius: 20px;
  padding: 1.5rem;
  box-shadow: var(--shadow-soft);
  margin-top: 2rem;
}

.theme-tabs .theme-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.theme-tabs .theme-btn {
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid transparent;
  border-radius: 999px;
  color: var(--color-muted);
  font-weight: 600;
  padding: 0.5rem 1.35rem;
  transition: background 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.theme-tabs .theme-btn:hover,
.theme-tabs .theme-btn:focus {
  color: #fff;
  border-color: rgba(255, 255, 255, 0.15);
}

.theme-tabs .theme-btn.active {
  background: var(--color-accent);
  color: #02101c;
  border-color: transparent;
  box-shadow: 0 16px 32px rgba(32, 164, 166, 0.35);
}

.theme-panels {
  position: relative;
}

.theme-panel {
  display: none;
  gap: 1.5rem;
  align-items: center;
}

.theme-panel.active {
  display: flex;
  flex-wrap: wrap;
}

.theme-panel figure {
  flex: 1 1 260px;
  margin: 0;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: var(--shadow-soft);
}

.theme-panel img {
  width: 100%;
  height: auto;
  display: block;
}

.theme-panel .panel-body {
  flex: 1 1 320px;
  color: var(--color-muted);
}

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

.btn-accent {
  background: var(--color-accent);
  border: 1px solid transparent;
  color: #031322;
  font-weight: 600;
  padding: 0.65rem 1.6rem;
  border-radius: 999px;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.btn-accent:hover,
.btn-accent:focus {
  color: #02101c;
  transform: translateY(-2px);
  box-shadow: 0 12px 24px rgba(32, 164, 166, 0.35);
}

.btn-outline-light {
  border-radius: 999px;
  padding: 0.65rem 1.6rem;
  border-width: 1.5px;
  font-weight: 600;
  border-color: rgba(255, 255, 255, 0.45);
  color: var(--color-text);
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease, color 0.2s ease;
}

.btn-outline-light:hover,
.btn-outline-light:focus {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: #02101c;
  transform: translateY(-2px);
  box-shadow: 0 12px 24px rgba(32, 164, 166, 0.28);
}

.quickfacts {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 0.9rem;
  color: var(--color-muted);
}

.quickfacts li {
  background: rgba(255, 255, 255, 0.05);
  border-radius: 12px;
  padding: 0.65rem 0.85rem;
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
}

.quickfacts i {
  color: var(--color-accent);
  margin-top: 0.15rem;
}

.quickfacts--four {
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
}

@media (min-width: 768px) {
  .quickfacts--four {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 992px) {
  .quickfacts--four {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.hero-portrait {
  position: relative;
  padding: 1.5rem;
  background: rgba(6, 14, 29, 0.6);
  border-radius: 24px;
  box-shadow: var(--shadow-soft);
}

.hero-image {
  border-radius: 18px;
  box-shadow: 0 22px 55px rgba(3, 8, 20, 0.55);
}

.hero-image-profile {
  width: 70%;
  max-width: 320px;
  margin: 0 auto 1.5rem;
}

@media (min-width: 992px) {
  .hero-image-profile {
    width: 85%;
    max-width: 360px;
    margin: 0 0 1.5rem auto;
  }
}

.social-links {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin-top: 1.25rem;
}

.social-links a {
  color: var(--color-text);
  opacity: 0.75;
  transition: opacity 0.2s ease, transform 0.2s ease;
}

.social-links a:hover {
  opacity: 1;
  transform: translateY(-3px);
}

/* News */
.news-section {
  background: var(--bg-surface);
  padding: 5rem 0 4rem;
}

.news-card {
  background: var(--bg-card);
  border-radius: 18px;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-soft);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
  height: 100%;
}

.news-card img {
  width: 100%;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  transition: transform 0.3s ease;
}

.news-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 22px 48px rgba(3, 8, 20, 0.5);
}

.news-card:hover img {
  transform: scale(1.05);
}

.news-card .news-body {
  padding: 1.5rem;
  color: var(--color-muted);
  font-size: 0.95rem;
}

.news-card .badge {
  background: rgba(32, 164, 166, 0.18);
  color: var(--color-accent-soft);
  border-radius: 999px;
  padding: 0.35rem 0.75rem;
  margin-right: 0.5rem;
}

.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 1rem;
  margin-top: 1.5rem;
}

.stat-card {
  background: rgba(255, 255, 255, 0.05);
  border-radius: 16px;
  padding: 1.25rem;
  text-align: center;
  border: 1px solid var(--color-border);
}

.stat-value {
  display: block;
  font-family: var(--font-heading);
  font-size: 2rem;
  color: #fff;
  margin-bottom: 0.35rem;
}

.stat-label {
  color: var(--color-muted);
  font-size: 0.9rem;
}

.content-card {
  background: var(--bg-card);
  border-radius: 18px;
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-soft);
  padding: 2rem;
  height: 100%;
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.content-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 24px 52px rgba(3, 8, 20, 0.55);
}

.content-card h3 {
  margin-bottom: 0.75rem;
  font-size: 1.4rem;
}

.content-card p {
  color: var(--color-muted);
  margin-bottom: 0;
}

.content-card .badge-soft {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.35rem 0.75rem;
  border-radius: 999px;
  background: rgba(32, 164, 166, 0.16);
  color: var(--color-accent-soft);
  font-size: 0.85rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

/* Research interests */
.research-section {
  background: var(--bg-body);
  padding: 5rem 0 4rem;
}

.research-item {
  border-radius: 16px;
  overflow: hidden;
  position: relative;
  background: var(--bg-card);
  box-shadow: var(--shadow-soft);
}

.research-item img {
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
  transition: transform 0.35s ease;
}

.research-item:hover img {
  transform: scale(1.05);
}

.ri-caption {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  padding: 0.9rem 1rem;
  background: linear-gradient(180deg, rgba(10, 16, 27, 0) 0%, rgba(10, 16, 27, 0.85) 100%);
  font-family: var(--font-base);
  font-weight: 600;
  letter-spacing: 0.01em;
}

/* Selected papers */
.papers-section {
  background: var(--bg-surface);
  padding: 5rem 0;
}

.paper-card {
  border: none;
  background: var(--bg-card);
  color: var(--color-text);
  border-radius: 18px;
  overflow: hidden;
  box-shadow: var(--shadow-soft);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.paper-card img {
  width: 100%;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  transition: transform 0.35s ease;
}

.paper-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 24px 52px rgba(3, 8, 20, 0.55);
}

.paper-card:hover img {
  transform: scale(1.05);
}

.paper-card .badge {
  border-radius: 999px;
  padding: 0.35rem 0.75rem;
  font-weight: 600;
}

.paper-card .card-body {
  padding: 1.5rem;
}

.paper-card .card-title {
  font-size: 1.05rem;
  line-height: 1.45;
  margin-bottom: 0;
}

/* Contact */
.contact-section {
  background: rgba(5, 12, 28, 0.85);
  backdrop-filter: blur(4px);
  padding: 5rem 0 4rem;
}

.contact-card {
  background: var(--bg-card);
  border-radius: 16px;
  padding: 2.25rem 1.75rem;
  height: 100%;
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-soft);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.contact-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 24px 52px rgba(3, 8, 20, 0.5);
}

.contact-card i {
  color: var(--color-accent);
  margin-bottom: 1rem;
}

.contact-card a {
  color: var(--color-text);
}

.contact-card a:hover {
  color: var(--color-accent-soft);
}

/* Team */
.team-section {
  background: var(--bg-surface);
  padding: 5rem 0;
}

.team-card {
  background: var(--bg-card);
  border-radius: 16px;
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-soft);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
  height: 100%;
}

.team-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 24px 52px rgba(3, 8, 20, 0.52);
}

.team-card-body {
  padding: 1.75rem;
}

.team-card-title {
  font-family: var(--font-heading);
  color: #fff;
  font-size: 1.25rem;
  margin-bottom: 0.35rem;
}

.team-card-subtitle {
  font-size: 0.82rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-accent-soft);
  margin-bottom: 0.75rem;
}

.team-card-text {
  font-size: 0.95rem;
  color: var(--color-muted);
}

.team-card-text a {
  color: var(--color-accent);
}

.team-card-text a:hover {
  color: var(--color-accent-soft);
}

.hero-metrics {
  margin-top: 2rem;
}

.metric-card {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--color-border);
  border-radius: 16px;
  padding: 1.25rem 1.5rem;
  text-align: left;
  box-shadow: var(--shadow-soft);
  height: 100%;
}

.metric-value {
  display: block;
  font-family: var(--font-heading);
  font-size: 1.75rem;
  color: #fff;
  margin-bottom: 0.35rem;
}

.metric-label {
  color: var(--color-muted);
  font-size: 0.9rem;
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  color: var(--color-muted);
}

.data-table thead {
  background: rgba(255, 255, 255, 0.05);
  color: #fff;
}

.data-table th,
.data-table td {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
  vertical-align: top;
}

.data-table tbody tr:last-child td {
  border-bottom: none;
}


.media-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 1.75rem 1.5rem;
  height: 100%;
  position: relative;
}

.media-card img {
  height: 72px;
  width: auto;
  margin-bottom: 1rem;
  object-fit: contain;
  filter: drop-shadow(0 10px 24px rgba(3, 8, 20, 0.35));
}

.media-card p {
  color: var(--color-muted);
  margin-bottom: 0;
}

.media-card a {
  margin-top: 0.75rem;
  font-weight: 600;
}

.accordion-card {
  border: 1px solid var(--color-border);
  border-radius: 16px;
  overflow: hidden;
  background: var(--bg-card);
  margin-bottom: 1rem;
}

.accordion-card .accordion-header {
  width: 100%;
  padding: 1.1rem 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  color: #fff;
  background: transparent;
  border: none;
  font-size: 1rem;
  text-align: left;
}

.accordion-card .accordion-header i {
  color: var(--color-accent);
  margin-right: 0.75rem;
}

.accordion-card .accordion-header .chevron {
  margin-right: 0;
  margin-left: 1rem;
  color: rgba(255, 255, 255, 0.55);
  transition: transform 0.25s ease;
}

.accordion-card .accordion-header.collapsed .chevron {
  transform: rotate(-90deg);
}

.accordion-card .accordion-body {
  padding: 1.25rem 1.5rem 1.5rem;
  color: var(--color-muted);
}

.accordion-card .list-unstyled {
  margin-bottom: 0;
}

.publication-list li {
  margin-bottom: 1rem;
  line-height: 1.6;
}

.publication-list li strong {
  color: #fff;
}

.publication-list li i {
  color: var(--color-accent);
  margin-right: 0.5rem;
}

/* Footer */
.site-footer {
  background: rgba(4, 9, 20, 0.95);
  color: var(--color-muted);
  padding: 2.5rem 0;
  font-size: 0.9rem;
}

.site-footer a {
  color: var(--color-accent);
}

/* Utilities */
.text-accent {
  color: var(--color-accent) !important;
}

.hr-light {
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

/* Responsive */
@media (max-width: 991px) {
  #mainNav .navbar-nav .nav-link {
    margin-left: 0;
  }

  .hero-section {
    padding-top: 7.5rem;
  }

  .hero-title {
    font-size: 2.5rem;
  }

  .hero-portrait {
    margin-top: 2.5rem;
  }

  .theme-panel {
    flex-direction: column;
  }
}

@media (max-width: 575px) {
  .section {
    padding: 4rem 0;
  }

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

  .hero-actions {
    flex-direction: column;
    align-items: stretch;
  }
}