/* CSS Custom Properties */
:root {
  /* Colors - Google-inspired palette */
  --primary-color: #1a73e8;
  --primary-dark: #1557b0;
  --primary-light: #e8f0fe;
  --secondary-color: #34a853;
  --accent-color: #fbbc04;
  --warning-color: #ea4335;
  
  /* Neutral colors */
  --text-primary: #202124;
  --text-secondary: #5f6368;
  --text-light: #80868b;
  --background-primary: #ffffff;
  --background-secondary: #f8f9fa;
  --background-tertiary: #e8eaed;
  --border-color: #dadce0;
  --divider-color: #e8eaed;
  
  /* Typography */
  --font-family-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-family-secondary: 'Merriweather', Georgia, serif;
  
  /* Font sizes */
  --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;
  
  /* 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;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-base: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  
  /* Border radius */
  --radius-sm: 0.25rem;
  --radius-base: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;
  
  /* Transitions */
  --transition-base: all 0.15s ease;
  --transition-slow: all 0.3s ease;
}

/* Reset and base styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family-primary);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--background-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-4);
}

@media (min-width: 768px) {
  .container {
    padding: 0 var(--space-6);
  }
}

/* Navigation */
.navbar {
  position: fixed;
  top: 0;
  width: 100%;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  transition: var(--transition-base);
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-4);
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 70px;
}

.nav-logo {
  text-decoration: none;
  color: var(--text-primary);
}

.logo-text {
  font-size: var(--text-xl);
  font-weight: 600;
  font-family: var(--font-family-secondary);
}

.nav-menu {
  display: flex;
  gap: var(--space-8);
  align-items: center;
}

.nav-link {
  text-decoration: none;
  color: var(--text-secondary);
  font-weight: 500;
  font-size: var(--text-sm);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-base);
  transition: var(--transition-base);
  position: relative;
}

.nav-link:hover,
.nav-link.active {
  color: var(--primary-color);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--primary-color);
  border-radius: var(--radius-full);
}

/* External Navigation Links */
.nav-link-external {
  display: flex;
  align-items: center;
  gap: 4px;
  color: var(--primary-color) !important;
  background: var(--primary-light);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-md);
}

.nav-link-external:hover {
  background: var(--primary-color);
  color: white !important;
}

.nav-link-external i {
  font-size: 14px;
}

/* Dropdown Navigation */
.nav-dropdown {
  position: relative;
  display: inline-block;
}

.nav-dropdown .nav-link i {
  font-size: 10px;
  margin-left: 4px;
  transition: var(--transition-base);
}

.nav-dropdown:hover .nav-link i {
  transform: rotate(180deg);
}

.dropdown-content {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  background-color: var(--background-primary);
  min-width: 250px;
  box-shadow: var(--shadow-lg);
  border-radius: var(--radius-md);
  padding: var(--space-2) 0;
  z-index: 1000;
  margin-top: 0;
  padding-top: var(--space-3);
}

.nav-dropdown:hover .dropdown-content,
.dropdown-content:hover {
  display: block;
}

.dropdown-content a {
  color: var(--text-secondary);
  padding: var(--space-3) var(--space-4);
  text-decoration: none;
  display: block;
  font-size: var(--text-sm);
  font-weight: 500;
  transition: var(--transition-base);
}

.dropdown-content a:hover {
  background-color: var(--background-secondary);
  color: var(--primary-color);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  cursor: pointer;
  gap: 4px;
}

.bar {
  width: 25px;
  height: 3px;
  background: var(--text-primary);
  border-radius: var(--radius-full);
  transition: var(--transition-base);
}

/* Mobile Navigation */
@media (max-width: 768px) {
  .nav-menu {
    position: fixed;
    left: -100%;
    top: 70px;
    flex-direction: column;
    background-color: var(--background-primary);
    width: 100%;
    text-align: center;
    transition: 0.3s;
    box-shadow: var(--shadow-lg);
    padding: var(--space-6) 0;
  }

  .nav-menu.active {
    left: 0;
  }
  
  .nav-dropdown {
    display: block;
  }
  
  .dropdown-content {
    position: static;
    display: none;
    box-shadow: none;
    background-color: var(--background-secondary);
    margin-top: var(--space-2);
  }
  
  .nav-dropdown.active .dropdown-content {
    display: block;
  }

  .nav-toggle {
    display: flex;
  }

  .nav-toggle.active .bar:nth-child(2) {
    opacity: 0;
  }

  .nav-toggle.active .bar:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
  }

  .nav-toggle.active .bar:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
  }
}

/* Hero Section */
.hero {
  margin-top: 70px;
  padding: var(--space-20) 0;
  background: linear-gradient(135deg, var(--background-primary) 0%, var(--background-secondary) 100%);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: url('data:image/svg+xml,<svg width="60" height="60" viewBox="0 0 60 60" xmlns="http://www.w3.org/2000/svg"><g fill="none" fill-rule="evenodd"><g fill="%23e8f0fe" fill-opacity="0.3"><circle cx="7" cy="7" r="3"/></g></svg>');
  opacity: 0.5;
}

.hero-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-16);
  align-items: center;
  position: relative;
  z-index: 1;
}

.hero-title {
  font-family: var(--font-family-secondary);
  margin-bottom: var(--space-4);
}

.greeting {
  display: block;
  font-size: var(--text-lg);
  color: var(--text-secondary);
  font-weight: 400;
  margin-bottom: var(--space-2);
}

.name {
  display: block;
  font-size: var(--text-5xl);
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.1;
}

.hero-subtitle {
  font-size: var(--text-xl);
  color: var(--primary-color);
  font-weight: 600;
  margin-bottom: var(--space-6);
}

.hero-description {
  font-size: var(--text-lg);
  color: var(--text-secondary);
  margin-bottom: var(--space-8);
  line-height: 1.7;
}

.hero-stats {
  display: flex;
  gap: var(--space-8);
  margin-bottom: var(--space-8);
}

.stat {
  text-align: center;
}

.stat-number {
  display: block;
  font-size: var(--text-3xl);
  font-weight: 700;
  color: var(--primary-color);
}

.stat-label {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.hero-buttons {
  display: flex;
  gap: var(--space-4);
  flex-wrap: wrap;
}

.hero-image {
  position: relative;
  display: flex;
  justify-content: center;
}

.profile-image {
  width: 350px;
  height: 350px;
  border-radius: var(--radius-xl);
  object-fit: cover;
  box-shadow: var(--shadow-xl);
  position: relative;
  z-index: 2;
}

.image-decoration {
  position: absolute;
  top: -20px;
  right: -20px;
  width: 350px;
  height: 350px;
  border: 3px solid var(--primary-color);
  border-radius: var(--radius-xl);
  z-index: 1;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-md);
  font-weight: 500;
  font-size: var(--text-sm);
  text-decoration: none;
  transition: var(--transition-base);
  border: 2px solid transparent;
  cursor: pointer;
  min-width: 120px;
}

.btn-primary {
  background: var(--primary-color);
  color: white;
}

.btn-primary:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.btn-secondary {
  background: transparent;
  color: var(--primary-color);
  border-color: var(--primary-color);
}

.btn-secondary:hover {
  background: var(--primary-color);
  color: white;
}

.btn-outline {
  background: transparent;
  color: var(--text-primary);
  border-color: var(--border-color);
}

.btn-outline:hover {
  border-color: var(--primary-color);
  color: var(--primary-color);
}

/* Sections */
.section-header {
  text-align: center;
  margin-bottom: var(--space-16);
}

.section-title {
  font-family: var(--font-family-secondary);
  font-size: var(--text-4xl);
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-4);
}

.section-subtitle {
  font-size: var(--text-lg);
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

.section-footer {
  text-align: center;
  margin-top: var(--space-12);
}

/* About Section */
.about {
  padding: var(--space-20) 0;
}

.about-content {
  max-width: 800px;
  margin: 0 auto;
}

.about-text p {
  font-size: var(--text-lg);
  color: var(--text-secondary);
  margin-bottom: var(--space-6);
  line-height: 1.7;
}

.research-interests {
  margin-top: var(--space-12);
}

.research-interests h3 {
  font-size: var(--text-2xl);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-6);
  text-align: center;
}

.interests-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-6);
}

.interest-item {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-4);
  background: var(--background-secondary);
  border-radius: var(--radius-lg);
  transition: var(--transition-base);
}

.interest-item:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.interest-item i {
  font-size: var(--text-xl);
  color: var(--primary-color);
  width: 24px;
  text-align: center;
}

.interest-item span {
  font-weight: 500;
  color: var(--text-primary);
}

/* Current Research Section */
.current-research {
  padding: var(--space-20) 0;
  background: var(--background-secondary);
}

.research-highlight {
  background: var(--background-primary);
  border-radius: var(--radius-xl);
  padding: var(--space-12);
  box-shadow: var(--shadow-lg);
}

.research-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-12);
  align-items: center;
}

.research-text h3 {
  font-size: var(--text-3xl);
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-6);
}

.research-text p {
  font-size: var(--text-lg);
  color: var(--text-secondary);
  margin-bottom: var(--space-6);
  line-height: 1.7;
}

.research-achievements {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}

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

.achievement i {
  font-size: var(--text-xl);
  color: var(--primary-color);
  margin-top: var(--space-1);
}

.achievement h4 {
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}

.achievement p {
  font-size: var(--text-base);
  color: var(--text-secondary);
}

.research-media {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}

.lab-image {
  width: 100%;
  height: 250px;
  object-fit: cover;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
}

.media-placeholder {
  display: flex;
  gap: var(--space-4);
}

.video-placeholder {
  flex: 1;
  height: 150px;
  background: var(--background-secondary);
  border-radius: var(--radius-lg);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: var(--text-light);
  border: 2px dashed var(--border-color);
}

.video-placeholder i {
  font-size: var(--text-3xl);
  margin-bottom: var(--space-2);
  color: var(--text-light);
}

/* Background Section */
.background {
  padding: var(--space-20) 0;
}

.background-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-16);
}

.education-section,
.experience-section {
  background: var(--background-primary);
  padding: var(--space-8);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-md);
}

.timeline {
  position: relative;
  padding-left: var(--space-12);
}

.timeline::before {
  content: '';
  position: absolute;
  left: 8px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--border-color);
}

.timeline-item {
  position: relative;
  margin-bottom: var(--space-8);
}

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

.timeline-marker {
  position: absolute;
  left: -20px;
  top: 4px;
  width: 16px;
  height: 16px;
  background: var(--background-primary);
  border: 3px solid var(--primary-color);
  border-radius: var(--radius-full);
  z-index: 1;
}

.timeline-marker.current {
  background: var(--primary-color);
}

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

.timeline-content h4 {
  font-size: var(--text-base);
  font-weight: 500;
  color: var(--primary-color);
  margin-bottom: var(--space-1);
}

.timeline-content .organization {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-bottom: var(--space-2);
}

.timeline-content .organization i {
  color: var(--primary-color);
  font-size: var(--text-base);
}

.timeline-content .organization h4 {
  margin: 0;
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--primary-color);
}

.timeline-content .location {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-bottom: var(--space-2);
}

.timeline-content .location i {
  color: var(--text-light);
  font-size: var(--text-sm);
}

.timeline-content .location span {
  font-size: var(--text-sm);
  color: var(--text-secondary);
}

.period {
  font-size: var(--text-sm);
  color: var(--text-light);
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-bottom: var(--space-2);
}

.period i {
  color: var(--text-light);
  font-size: var(--text-sm);
}

.timeline-content p.description {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: 1.6;
  margin-top: var(--space-2);
  padding-left: var(--space-6);
  border-left: 2px solid var(--border-color);
}

.timeline-content ul.description-list {
  list-style: none;
  padding: 0;
  margin: var(--space-3) 0 0 0;
}

.timeline-content ul.description-list li {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--space-2);
  padding-left: var(--space-6);
  position: relative;
}

.timeline-content ul.description-list li::before {
  content: "•";
  color: var(--primary-color);
  font-weight: bold;
  position: absolute;
  left: var(--space-2);
}

.timeline-content p {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: 1.6;
}

/* Mentoring and Academic Contributions */
.mentoring {
  padding: var(--space-20) 0;
  background: var(--background-secondary);
}

.mentoring-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-8);
  margin-top: var(--space-12);
}

.mentoring-card {
  background: var(--background-primary);
  padding: var(--space-8);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  transition: var(--transition-base);
  border-top: 4px solid var(--primary-color);
}

.mentoring-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.mentoring-card .card-icon {
  width: 60px;
  height: 60px;
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-6);
}

.mentoring-card .card-icon i {
  font-size: var(--text-2xl);
  color: var(--background-primary);
}

.mentoring-card h3 {
  font-family: var(--font-family-secondary);
  font-size: var(--text-xl);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-4);
}

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

.mentoring-list li {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--space-3);
  padding-left: var(--space-6);
  position: relative;
}

.mentoring-list li::before {
  content: "✓";
  color: var(--primary-color);
  font-weight: bold;
  position: absolute;
  left: 0;
}

.mentoring-list li strong {
  color: var(--text-primary);
  font-weight: 600;
}

/* Recent Publications */
.recent-publications {
  padding: var(--space-20) 0;
  background: var(--background-secondary);
}

.publications-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: var(--space-8);
}

.publication-card {
  background: var(--background-primary);
  padding: var(--space-6);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  transition: var(--transition-base);
}

.publication-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.publication-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-4);
}

.publication-type {
  background: var(--primary-light);
  color: var(--primary-color);
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.publication-year {
  font-size: var(--text-sm);
  color: var(--text-light);
  font-weight: 600;
}

.publication-card h3 {
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-3);
  line-height: 1.4;
}

.authors {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  margin-bottom: var(--space-2);
}

.journal {
  font-size: var(--text-sm);
  color: var(--primary-color);
  font-weight: 500;
  font-style: italic;
}

/* Footer */
.footer {
  background: var(--text-primary);
  color: white;
  padding: var(--space-16) 0 var(--space-8);
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--space-8);
  margin-bottom: var(--space-8);
}

.footer-section h4 {
  font-size: var(--text-lg);
  font-weight: 600;
  margin-bottom: var(--space-4);
  color: white;
}

.footer-section p {
  color: #e8eaed;
  margin-bottom: var(--space-2);
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.footer-section i {
  width: 16px;
  text-align: center;
}

.social-links {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.social-links a {
  color: #e8eaed;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: var(--space-2);
  transition: var(--transition-base);
}

.social-links a:hover {
  color: var(--primary-light);
}

.footer-bottom {
  text-align: center;
  padding-top: var(--space-8);
  border-top: 1px solid #5f6368;
  color: #e8eaed;
}

/* Responsive Design */
@media (max-width: 768px) {
  .hero-content {
    grid-template-columns: 1fr;
    text-align: center;
    gap: var(--space-12);
  }

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

  .name {
    font-size: var(--text-4xl) !important;
  }

  .profile-image {
    width: 250px;
    height: 250px;
  }

  .image-decoration {
    width: 250px;
    height: 250px;
  }

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

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

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

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

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

@media (max-width: 480px) {
  :root {
    --space-20: 3rem;
    --space-16: 2.5rem;
    --space-12: 2rem;
  }

  .container {
    padding: 0 var(--space-3);
  }

  .nav-container {
    padding: 0 var(--space-3);
  }

  .name {
    font-size: var(--text-3xl) !important;
  }

  .section-title {
    font-size: var(--text-3xl);
  }

  .profile-image {
    width: 200px;
    height: 200px;
  }

  .image-decoration {
    width: 200px;
    height: 200px;
  }

  .research-highlight {
    padding: var(--space-6);
  }

  .education-section,
  .experience-section {
    padding: var(--space-6);
  }
}

/* Loading animations */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in-up {
  animation: fadeInUp 0.6s ease-out;
}

/* Page Layout Fixes */
main {
  min-height: calc(100vh - 70px);
  margin-top: 70px;
}

/* Page-specific hero sections */
.research-hero,
.publications-hero,
.teaching-hero,
.contact-hero {
  padding: var(--space-20) 0 var(--space-16) 0;
  background: linear-gradient(135deg, var(--background-primary) 0%, var(--background-secondary) 100%);
  position: relative;
}

.research-hero-content,
.publications-hero-content,
.teaching-hero-content,
.contact-hero-content {
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.research-title,
.publications-title,
.teaching-title,
.contact-title {
  font-family: var(--font-family-secondary);
  font-size: var(--text-5xl);
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-6);
  line-height: 1.2;
}

.research-subtitle,
.publications-subtitle,
.teaching-subtitle,
.contact-subtitle {
  font-size: var(--text-lg);
  color: var(--text-secondary);
  line-height: 1.6;
  max-width: 600px;
  margin: 0 auto;
}

/* Section spacing */
section {
  padding: var(--space-16) 0;
}

/* Main Research Project Styles */
.main-research {
  padding: var(--space-16) 0;
  background: var(--background-primary);
}

.research-project {
  max-width: 1400px;
  margin: 0 auto;
}

.project-header {
  text-align: center;
  padding: var(--space-3) var(--space-6);
  background: var(--background-secondary);
  margin-bottom: 0;
}

.project-status {
  display: inline-block;
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  color: var(--background-primary);
  padding: var(--space-2) var(--space-6);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 600;
  margin-bottom: var(--space-4);
}

.project-title {
  font-family: var(--font-family-secondary);
  font-size: var(--text-2xl);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-1);
  line-height: 1.2;
}

.project-duration {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  font-weight: 500;
}

/* Main Experimental Video Container */
.main-video-container {
  position: relative;
  width: 100%;
  height: 600px;
  margin-bottom: var(--space-12);
  border-radius: var(--radius-xl);
  overflow: hidden;
  box-shadow: var(--shadow-xl);
}

.main-experimental-video {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.video-overlay {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  width: 100%;
  max-width: 100%;
  background: linear-gradient(135deg, rgba(26, 35, 126, 0.6) 0%, rgba(13, 71, 161, 0.5) 100%);
  backdrop-filter: blur(8px);
  border-radius: 0;
  padding: var(--space-4) var(--space-8);
  box-shadow: 0 -4px 20px rgba(0, 0, 0, 0.2);
}

.project-content-overlay {
  color: var(--background-primary);
  max-width: 1200px;
  margin: 0 auto;
}

.project-overview-overlay {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.project-overview-overlay h3 {
  font-family: var(--font-family-secondary);
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--background-primary);
  margin-bottom: 0;
  text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.4);
  opacity: 0;
  animation: fadeInText 0.8s ease-in-out 0.5s forwards;
}

.overlay-bullets {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  min-height: 24px;
  position: relative;
  height: 24px;
}

.bullet-item {
  font-size: var(--text-sm);
  line-height: 1.5;
  color: rgba(255, 255, 255, 0.95);
  margin-bottom: 0;
  text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.4);
  opacity: 0;
  animation: bulletFadeInOut 25s ease-in-out infinite;
  animation-fill-mode: both;
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
}

.bullet-item[data-delay="0"] {
  animation-delay: 0s;
}

.bullet-item[data-delay="1"] {
  animation-delay: 5s;
}

.bullet-item[data-delay="2"] {
  animation-delay: 10s;
}

.bullet-item[data-delay="3"] {
  animation-delay: 15s;
}

.bullet-item[data-delay="4"] {
  animation-delay: 20s;
}

@keyframes bulletFadeInOut {
  0% {
    opacity: 0;
    transform: translateY(10px);
  }
  4% {
    opacity: 1;
    transform: translateY(0);
  }
  16% {
    opacity: 1;
    transform: translateY(0);
  }
  20% {
    opacity: 0;
    transform: translateY(-10px);
  }
  100% {
    opacity: 0;
    transform: translateY(-10px);
  }
}

@keyframes fadeInText {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Experiment Videos Grid */
.experiment-videos {
  margin-bottom: var(--space-12);
}

.experiment-videos .section-subtitle {
  font-family: var(--font-family-secondary);
  font-size: var(--text-2xl);
  font-weight: 600;
  color: var(--text-primary);
  text-align: center;
  margin-bottom: var(--space-8);
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: var(--space-8);
}

.video-item {
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-md);
  transition: var(--transition-base);
  background: var(--background-secondary);
}

.video-item:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.experiment-video {
  width: 100%;
  height: 500px;
  object-fit: cover;
  display: block;
}

.video-caption {
  padding: var(--space-4);
  text-align: center;
  font-size: var(--text-base);
  font-weight: 500;
  color: var(--text-primary);
  background: var(--background-primary);
}

/* CFD Simulation Section */
.cfd-simulation {
  padding: var(--space-12) 0;
  margin-top: var(--space-12);
}

.cfd-simulation .section-subtitle {
  font-family: var(--font-family-secondary);
  font-size: var(--text-2xl);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-8);
  text-align: center;
}

.cfd-content {
  display: flex;
  justify-content: center;
  align-items: center;
  margin-top: var(--space-8);
}

.cfd-video-container {
  position: relative;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  background: var(--background-secondary);
  width: 120%;
  max-width: 1400px;
}

.cfd-video {
  width: 100%;
  height: 700px;
  object-fit: cover;
  display: block;
}

.cfd-overlay {
  position: absolute;
  top: var(--space-4);
  left: var(--space-4);
  background: rgba(26, 35, 126, 0.75);
  backdrop-filter: blur(10px);
  padding: var(--space-4) var(--space-6);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  max-width: 400px;
}

.cfd-overlay .video-caption {
  color: white;
  font-weight: 700;
  font-size: var(--text-lg);
  margin: 0 0 var(--space-3) 0;
  padding: 0;
  background: transparent;
  text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
  border-bottom: 2px solid rgba(255, 255, 255, 0.3);
  padding-bottom: var(--space-2);
}

.cfd-overlay .cfd-description {
  padding: 0;
  background: transparent;
  border-radius: 0;
  box-shadow: none;
  margin: 0;
  text-align: left;
}

.cfd-overlay .cfd-description h4 {
  font-size: var(--text-base);
  font-weight: 600;
  color: white;
  margin-bottom: var(--space-2);
  text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.5);
}

.cfd-overlay .cfd-description p {
  color: rgba(255, 255, 255, 0.95);
  line-height: 1.5;
  font-size: var(--text-sm);
  margin: 0;
  text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.5);
}

/* Wire-Mesh Sensor Section */
.wms-section {
  padding: var(--space-12) 0;
  margin-top: var(--space-12);
  background: var(--background-secondary);
  border-radius: var(--radius-xl);
  padding: var(--space-12);
}

.wms-section .section-subtitle {
  font-family: var(--font-family-secondary);
  font-size: var(--text-2xl);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-6);
  text-align: center;
}

.wms-layout {
  display: flex;
  justify-content: center;
  align-items: center;
  margin-top: var(--space-8);
}

.wms-main-container {
  position: relative;
  width: 110%;
  max-width: 1200px;
}

.wms-location-img {
  width: 100%;
  height: auto;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  display: block;
}

.wms-overlay-videos {
  position: absolute;
  top: var(--space-4);
  left: var(--space-4);
  display: flex;
  flex-direction: row;
  gap: var(--space-3);
  z-index: 10;
}

.wms-overlay-item {
  background: var(--background-primary);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
  border: 2px solid var(--background-primary);
}

.wms-overlay-video {
  width: 200px;
  height: 150px;
  object-fit: cover;
  display: block;
}

.wms-overlay-caption {
  padding: var(--space-2) var(--space-3);
  text-align: center;
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--text-primary);
  background: var(--background-primary);
  margin: 0;
}

.wms-description {
  padding: var(--space-6);
  background: rgba(26, 35, 126, 0.75);
  backdrop-filter: blur(10px);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  margin-bottom: var(--space-8);
  text-align: center;
  max-width: 900px;
  margin-left: auto;
  margin-right: auto;
}

.wms-description h4 {
  font-size: var(--text-xl);
  font-weight: 600;
  color: white;
  margin-bottom: var(--space-3);
  text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
}

.wms-description .image-caption {
  font-size: var(--text-base);
  color: rgba(255, 255, 255, 0.95);
  line-height: 1.6;
  font-style: normal;
  text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.5);
}

.image-caption {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  font-style: italic;
  margin-top: var(--space-2);
}

.wms-videos {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}

.wms-video {
  width: 100%;
  height: 300px;
  object-fit: cover;
  display: block;
}

/* Project Publications */
.project-publications {
  background: var(--background-secondary);
  padding: var(--space-12);
  border-radius: var(--radius-xl);
}

.project-publications .section-subtitle {
  font-family: var(--font-family-secondary);
  font-size: var(--text-2xl);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-8);
  text-align: center;
}

.publications-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}

.pub-item {
  display: flex;
  gap: var(--space-6);
  padding: var(--space-6);
  background: var(--background-primary);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  transition: var(--transition-base);
}

.pub-item:hover {
  box-shadow: var(--shadow-md);
  transform: translateX(4px);
}

.pub-year {
  flex-shrink: 0;
  width: 60px;
  height: 60px;
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  color: var(--background-primary);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: var(--text-lg);
}

.pub-content h4 {
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-2);
  line-height: 1.4;
}

.pub-authors {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  margin-bottom: var(--space-1);
}

.pub-journal {
  font-size: var(--text-sm);
  color: var(--primary-color);
  font-weight: 500;
  font-style: italic;
}

/* Footer improvements */
.footer {
  margin-top: var(--space-20);
}

/* Responsive adjustments for page titles */
@media (max-width: 768px) {
  .research-title,
  .publications-title,
  .teaching-title,
  .contact-title {
    font-size: var(--text-3xl);
  }
  
  .research-hero,
  .publications-hero,
  .teaching-hero,
  .contact-hero {
    padding: var(--space-12) 0 var(--space-8) 0;
  }
  
  .mentoring-grid {
    grid-template-columns: 1fr;
    gap: var(--space-6);
  }
  
  .mentoring-card {
    padding: var(--space-6);
  }
  
  .main-video-container {
    height: 400px;
  }
  
  .video-overlay {
    padding: var(--space-3) var(--space-4);
  }
  
  .project-overview-overlay h3 {
    font-size: var(--text-base);
  }
  
  .bullet-item {
    font-size: var(--text-xs);
    line-height: 1.4;
  }
  
  .video-grid {
    grid-template-columns: 1fr;
  }
  
  .experiment-video {
    height: 250px;
  }
  
  .cfd-content {
    grid-template-columns: 1fr;
  }
  
  .cfd-video-container {
    width: 100%;
  }
  
  .cfd-video {
    height: 350px;
  }
  
  .cfd-overlay {
    max-width: 90%;
    padding: var(--space-3) var(--space-4);
  }
  
  .cfd-overlay .video-caption {
    font-size: var(--text-base);
  }
  
  .cfd-overlay .cfd-description h4 {
    font-size: var(--text-sm);
  }
  
  .cfd-overlay .cfd-description p {
    font-size: var(--text-xs);
  }
  
  .wms-layout {
    justify-content: center;
  }
  
  .wms-main-container {
    width: 100%;
  }
  
  .wms-overlay-videos {
    position: relative;
    top: 0;
    left: 0;
    margin-top: var(--space-4);
  }
  
  .wms-overlay-video {
    width: 100%;
    height: 200px;
  }
  
  .project-title {
    font-size: var(--text-2xl);
  }
  
  .pub-item {
    flex-direction: column;
    gap: var(--space-4);
  }
  
  .pub-year {
    width: 50px;
    height: 50px;
    font-size: var(--text-base);
  }
}

/* Focus styles for accessibility */
.btn:focus,
.nav-link:focus {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}

/* Print styles */
@media print {
  .navbar,
  .footer {
    display: none;
  }
  
  .hero {
    margin-top: 0;
  }
  
  * {
    color: black !important;
    background: white !important;
  }
}