/* CSS Variables */
:root {
  --primary-color: #003366;
  --secondary-color: #f4b41a;
  --accent-color: #0066cc;
  --text-color: #333;
  --text-light: #666;
  --bg-color: #fff;
  --bg-light: #f8f9fa;
  --border-color: #e0e0e0;
  --header-height: 70px;
  --container-width: 1200px;
  --transition: 0.3s ease;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-color);
  background: var(--bg-color);
}

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

a:hover {
  color: var(--primary-color);
}

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

.container {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* Header */
.site-header {
  background: var(--primary-color);
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.header-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: var(--header-height);
}

.site-logo {
  display: flex;
  align-items: baseline;
  color: white;
  font-weight: 700;
}

.logo-text {
  font-size: 2rem;
  color: var(--secondary-color);
}

.logo-text sup {
  font-size: 1rem;
}

.logo-subtitle {
  font-size: 1.5rem;
  margin-left: 4px;
  color: white;
}

.site-nav .nav-links {
  display: flex;
  list-style: none;
  gap: 30px;
}

.site-nav a {
  color: white;
  font-weight: 500;
  padding: 8px 0;
  position: relative;
}

.site-nav a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--secondary-color);
  transition: width var(--transition);
}

.site-nav a:hover::after,
.site-nav a.active::after {
  width: 100%;
}

.site-nav a:hover,
.site-nav a.active {
  color: var(--secondary-color);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 5px;
}

.nav-toggle span {
  display: block;
  width: 25px;
  height: 2px;
  background: white;
  transition: var(--transition);
}

/* Hero Section */
.hero {
  background: linear-gradient(135deg, var(--primary-color) 0%, #004080 100%);
  color: white;
  padding: 80px 0;
  text-align: center;
}

.hero h1 {
  font-size: 3rem;
  margin-bottom: 10px;
}

.hero .subtitle {
  font-size: 1.5rem;
  opacity: 0.9;
  margin-bottom: 30px;
}

.hero .tagline {
  font-size: 1.15rem;
  font-style: italic;
  max-width: 1000px;
  margin: 0 auto;
  opacity: 0.85;
  white-space: nowrap;
}

@media (max-width: 1000px) {
  .hero .tagline {
    white-space: normal;
    max-width: 90%;
  }
}

/* Home Images Strip */
.home-images {
  padding: 40px 0;
  background: var(--bg-light);
}

.image-strip {
  display: flex;
  gap: 20px;
  justify-content: center;
  align-items: stretch;
}

.image-strip img {
  height: 220px;
  width: auto;
  object-fit: cover;
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

@media (max-width: 900px) {
  .image-strip {
    flex-direction: column;
    align-items: center;
  }

  .image-strip img {
    height: auto;
    width: 100%;
    max-width: 500px;
  }
}

/* Section Styles */
section {
  padding: 60px 0;
}

section:nth-child(even) {
  background: var(--bg-light);
}

.section-title {
  font-size: 2rem;
  color: var(--primary-color);
  margin-bottom: 30px;
  padding-bottom: 10px;
  border-bottom: 3px solid var(--secondary-color);
  display: inline-block;
}

/* Research Areas */
.research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 30px;
  margin-top: 30px;
}

.research-card {
  background: white;
  padding: 30px;
  border-radius: 10px;
  box-shadow: 0 4px 15px rgba(0,0,0,0.08);
  transition: transform var(--transition), box-shadow var(--transition);
}

.research-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 25px rgba(0,0,0,0.12);
}

.research-card h3 {
  color: var(--primary-color);
  margin-bottom: 15px;
  font-size: 1.25rem;
}

.research-card p {
  color: var(--text-light);
}

/* Applications */
.applications-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 25px;
}

.application-item {
  display: flex;
  align-items: flex-start;
  gap: 15px;
  padding: 20px;
  background: white;
  border-radius: 8px;
  border-left: 4px solid var(--secondary-color);
}

.application-item h3 {
  font-size: 1.1rem;
  color: var(--primary-color);
  margin-bottom: 5px;
}

/* Highlights */
.highlights-section {
  background: var(--bg-light);
}

.highlights-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 15px;
}

.highlights-list.horizontal {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.highlights-list.horizontal li {
  width: 100%;
}

.highlights-list li {
  background: white;
  padding: 18px 22px;
  border-radius: 8px;
  border-left: 4px solid var(--secondary-color);
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
  font-weight: 500;
  color: var(--primary-color);
}

.highlights-list li a {
  color: var(--primary-color);
  text-decoration: none;
  border-bottom: 2px solid transparent;
  transition: border-color var(--transition);
}

.highlights-list li a:hover {
  border-bottom-color: var(--secondary-color);
}

/* Highlights & Gallery Page */
.highlights-page-section,
.gallery-page-section {
  margin-bottom: 50px;
}

.highlights-page-section h2,
.gallery-page-section h2 {
  color: var(--primary-color);
  border-bottom: 2px solid var(--secondary-color);
  padding-bottom: 10px;
  margin-bottom: 25px;
  font-size: 1.75rem;
}

/* Collaborators */
.collaborators {
  display: flex;
  flex-wrap: wrap;
  gap: 30px;
  justify-content: center;
  margin-top: 30px;
}

.collaborator {
  padding: 15px 30px;
  background: white;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
  font-weight: 500;
  color: var(--primary-color);
}

/* People Page */
.people-section {
  margin-bottom: 50px;
}

.people-section h2 {
  color: var(--primary-color);
  border-bottom: 2px solid var(--secondary-color);
  padding-bottom: 10px;
  margin-bottom: 25px;
}

.people-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 25px;
}

.person-card {
  background: white;
  padding: 25px;
  border-radius: 10px;
  box-shadow: 0 3px 12px rgba(0,0,0,0.08);
  text-align: center;
  transition: transform var(--transition);
}

.person-card:hover {
  transform: translateY(-3px);
}

.people-grid.flat {
  margin-bottom: 50px;
}

.person-avatar {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  background: var(--bg-light);
  margin: 0 auto 15px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.5rem;
  color: var(--primary-color);
  object-fit: cover;
}

img.person-avatar {
  border: 3px solid var(--bg-light);
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.person-card h3 {
  color: var(--primary-color);
  margin-bottom: 5px;
}

.person-card .role {
  color: var(--text-light);
  font-size: 0.9rem;
  margin-bottom: 10px;
}

.person-card .affiliation {
  font-size: 0.85rem;
  color: var(--text-light);
}

/* Alumni Section */
.alumni-section {
  margin-top: 50px;
  padding-top: 40px;
  border-top: 2px solid var(--border-color);
}

.alumni-section h2 {
  color: var(--primary-color);
  margin-bottom: 25px;
  font-size: 1.75rem;
}

.alumni-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.alumni-list li {
  padding: 15px 0;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: baseline;
}

.alumni-list li:last-child {
  border-bottom: none;
}

.alumni-name {
  font-weight: 600;
  color: var(--primary-color);
  min-width: 180px;
}

.alumni-details {
  color: var(--text-light);
  font-size: 0.95rem;
}

@media (max-width: 600px) {
  .alumni-list li {
    flex-direction: column;
    gap: 5px;
  }

  .alumni-name {
    min-width: auto;
  }
}

/* Publications */
.pub-year {
  margin-bottom: 40px;
}

.pub-year h2 {
  color: var(--primary-color);
  border-left: 4px solid var(--secondary-color);
  padding-left: 15px;
  margin-bottom: 20px;
}

.publication {
  background: white;
  padding: 20px;
  margin-bottom: 15px;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}

.publication h3 {
  font-size: 1.1rem;
  color: var(--primary-color);
  margin-bottom: 8px;
}

.publication h3 a {
  color: var(--primary-color);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition);
}

.publication h3 a:hover {
  border-bottom-color: var(--secondary-color);
}

.publication .authors {
  color: var(--text-light);
  font-size: 0.95rem;
  margin-bottom: 5px;
}

.publication .venue {
  font-style: italic;
  color: var(--text-light);
  font-size: 0.9rem;
}

.publication .award {
  display: inline-block;
  background: var(--secondary-color);
  color: var(--primary-color);
  padding: 3px 10px;
  border-radius: 4px;
  font-size: 0.8rem;
  font-weight: 600;
  margin-top: 8px;
}

/* News */
.news-list {
  max-width: 800px;
}

.news-item {
  background: white;
  padding: 25px;
  margin-bottom: 20px;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.06);
  border-left: 4px solid var(--secondary-color);
}

.news-item .date {
  color: var(--accent-color);
  font-weight: 600;
  font-size: 0.9rem;
  margin-bottom: 8px;
}

.news-item h3 {
  color: var(--primary-color);
  margin-bottom: 10px;
}

.news-item p {
  color: var(--text-light);
}

/* Prospective Members */
.info-section {
  background: white;
  padding: 30px;
  margin-bottom: 25px;
  border-radius: 10px;
  box-shadow: 0 3px 12px rgba(0,0,0,0.08);
}

.info-section h2 {
  color: var(--primary-color);
  margin-bottom: 15px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--secondary-color);
}

.info-section ul {
  margin-left: 20px;
  color: var(--text-light);
}

.info-section li {
  margin-bottom: 10px;
}

.cta-button {
  display: inline-block;
  background: var(--primary-color);
  color: white;
  padding: 12px 30px;
  border-radius: 6px;
  font-weight: 600;
  transition: background var(--transition);
  margin-top: 15px;
}

.cta-button:hover {
  background: var(--accent-color);
  color: white;
}

/* Gallery */
.gallery-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
}

.gallery-item {
  aspect-ratio: 4/3;
  background: var(--bg-light);
  border-radius: 8px;
  overflow: hidden;
}

.gallery-item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* Page Header */
.page-header {
  background: linear-gradient(135deg, var(--primary-color) 0%, #004080 100%);
  color: white;
  padding: 50px 0;
  margin-bottom: 40px;
}

.page-header h1 {
  font-size: 2.5rem;
}

.page-header p {
  opacity: 0.9;
  margin-top: 10px;
}

/* Footer */
.site-footer {
  background: var(--primary-color);
  color: white;
  padding: 50px 0 20px;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 40px;
  margin-bottom: 30px;
}

.footer-content h3 {
  color: var(--secondary-color);
  margin-bottom: 15px;
}

.footer-content a {
  color: white;
}

.footer-content a:hover {
  color: var(--secondary-color);
}

.footer-bottom {
  text-align: center;
  padding-top: 20px;
  border-top: 1px solid rgba(255,255,255,0.1);
  opacity: 0.8;
  font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 768px) {
  .nav-toggle {
    display: flex;
  }

  .nav-links {
    position: absolute;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: var(--primary-color);
    flex-direction: column;
    padding: 20px;
    gap: 15px;
    display: none;
  }

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

  .hero h1 {
    font-size: 2rem;
  }

  .hero .subtitle {
    font-size: 1.2rem;
  }

  .section-title {
    font-size: 1.5rem;
  }

  section {
    padding: 40px 0;
  }
}