/* Academic Website - Main CSS */

/* Import Google Fonts */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Playfair+Display:wght@400;500;600;700&display=swap');

/* CSS Custom Properties */
:root {
  /* Colors */
  --primary-color: #1e3a8a;
  --secondary-color: #6b7280;
  --accent-color: #f59e0b;
  --background-color: #ffffff;
  --text-color: #1f2937;
  --text-light: #6b7280;
  --border-color: #e5e7eb;
  --shadow-light: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
  --shadow-medium: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-large: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  
  /* Typography */
  --font-serif: 'Playfair Display', serif;
  --font-sans: 'Inter', sans-serif;
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  
  /* Border radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  
  /* Transitions */
  --transition-fast: 0.15s ease-in-out;
  --transition-normal: 0.3s ease-in-out;
  --transition-slow: 0.5s ease-in-out;
}

/* Reset and Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  /* font-family: var(--font-sans); */
  font-family: 'Ubuntu', sans-serif;
  font-size: 1rem;
  line-height: 1.6;
  color: var(--text-color);
  background-color: var(--background-color);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  /* font-family: var(--font-serif); */
  font-family: 'Ubuntu', sans-serif;
  font-weight: 600;
  line-height: 1.2;
  margin-bottom: var(--spacing-md);
  color: var(--text-color);
}

h1 {
  font-size: 3rem;
  font-weight: 700;
  margin-bottom: var(--spacing-lg);
}

h2 {
  font-size: 2.25rem;
  margin-bottom: var(--spacing-lg);
}

h3 {
  font-size: 1.875rem;
}

h4 {
  font-size: 1.5rem;
}

h5 {
  font-size: 1.25rem;
}

h6 {
  font-size: 1.125rem;
}

p {
  margin-bottom: var(--spacing-md);
  color: var(--text-color);
}

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

a:hover {
  color: var(--accent-color);
  text-decoration: underline;
}

/* Layout Components */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

.section {
  padding: var(--spacing-3xl) 0;
}

.section-title {
  text-align: center;
  margin-bottom: var(--spacing-2xl);
  position: relative;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -var(--spacing-md);
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 3px;
  background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
  border-radius: var(--radius-sm);
}

/* Header and Navigation */
.header {
  background: var(--background-color);
  box-shadow: var(--shadow-light);
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  transition: all var(--transition-normal);
}

.header.scrolled {
  box-shadow: var(--shadow-medium);
  backdrop-filter: blur(10px);
  background: rgba(255, 255, 255, 0.95);
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-md) 0;
}

.logo {
  /* font-family: var(--font-serif); */
  font-family: "Papyrus", "Comic Sans MS", "Fantasy", sans-serif;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-color);
  text-decoration: none;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: var(--spacing-xl);
}

.nav-item a {
  font-weight: 500;
  color: var(--text-color);
  transition: color var(--transition-fast);
  position: relative;
}

.nav-item a:hover,
.nav-item a.active {
  color: var(--primary-color);
  text-decoration: none;
}

.nav-item a::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent-color);
  transition: width var(--transition-fast);
}

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

.mobile-menu-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--text-color);
  cursor: pointer;
}

/* Hero Section */
.hero {
  padding: calc(80px + var(--spacing-3xl)) 0 var(--spacing-3xl);
  background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
  text-align: center;
}

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

.hero-image {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  object-fit: cover;
  margin: 0 auto var(--spacing-xl);
  box-shadow: var(--shadow-large);
  border: 4px solid var(--background-color);
}

.hero-title {
  font-size: 3.5rem;
  margin-bottom: var(--spacing-md);
  background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--text-light);
  margin-bottom: var(--spacing-xl);
  font-weight: 400;
}

.hero-description {
  font-size: 1.125rem;
  color: var(--text-color);
  margin-bottom: var(--spacing-2xl);
  line-height: 1.7;
}

/* Buttons */
.btn {
  display: inline-block;
  padding: var(--spacing-md) var(--spacing-xl);
  border-radius: var(--radius-md);
  font-weight: 500;
  text-decoration: none;
  transition: all var(--transition-fast);
  cursor: pointer;
  border: none;
  font-size: 1rem;
  line-height: 1;
}

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

.btn-primary:hover {
  background: #1e40af;
  transform: translateY(-2px);
  box-shadow: var(--shadow-medium);
  text-decoration: none;
  color: white;
}

.btn-secondary {
  background: transparent;
  color: var(--primary-color);
  border: 2px solid var(--primary-color);
}

.btn-secondary:hover {
  background: var(--primary-color);
  color: white;
  text-decoration: none;
}

.btn-group {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  flex-wrap: wrap;
}

/* Cards */
.card {
  background: var(--background-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-light);
  padding: var(--spacing-xl);
  transition: all var(--transition-normal);
  border: 1px solid var(--border-color);
}

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

.card-title {
  font-size: 1.5rem;
  margin-bottom: var(--spacing-md);
  color: var(--primary-color);
}

.card-meta {
  font-size: 0.875rem;
  color: var(--text-light);
  margin-bottom: var(--spacing-md);
}

/* Grid Layouts */
.grid {
  display: grid;
  gap: var(--spacing-xl);
}

.grid-2 {
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.grid-3 {
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

/* Content Sections */
.content-section {
  margin-bottom: var(--spacing-3xl);
}

.content-grid {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: var(--spacing-2xl);
  align-items: start;
}

.sidebar {
  position: sticky;
  top: 100px;
}

.sidebar-nav {
  list-style: none;
  padding: var(--spacing-lg);
  background: var(--background-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-light);
}

.sidebar-nav li {
  margin-bottom: var(--spacing-sm);
}

.sidebar-nav a {
  display: block;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.sidebar-nav a:hover,
.sidebar-nav a.active {
  background: var(--primary-color);
  color: white;
  text-decoration: none;
}

/* Publications and Research */
.publication-item {
  padding: var(--spacing-lg);
  border-left: 4px solid var(--primary-color);
  margin-bottom: var(--spacing-lg);
  background: #f8fafc;
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

.publication-title {
  font-weight: 600;
  color: var(--primary-color);
  margin-bottom: var(--spacing-sm);
}

.publication-authors {
  color: var(--text-light);
  font-style: italic;
  margin-bottom: var(--spacing-sm);
}

.publication-venue {
  font-weight: 500;
  margin-bottom: var(--spacing-sm);
}

.publication-links {
  display: flex;
  gap: var(--spacing-md);
  flex-wrap: wrap;
}

.publication-links a {
  font-size: 0.875rem;
  padding: var(--spacing-xs) var(--spacing-sm);
  background: var(--primary-color);
  color: white;
  border-radius: var(--radius-sm);
  text-decoration: none;
  transition: background var(--transition-fast);
}

.publication-links a:hover {
  background: var(--accent-color);
}

/* Timeline */
.timeline {
  position: relative;
  padding-left: var(--spacing-xl);
}

.timeline::before {
  content: '';
  position: absolute;
  left: 0.75rem;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--primary-color);
}

.timeline-item {
  position: relative;
  padding-left: 2rem;
  margin-bottom: 1.5rem;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -0.5rem;
  top: 0.125rem;
  width: var(--spacing-md);
  height: var(--spacing-md);
  background: var(--accent-color);
  border-radius: 50%;
  border: 3px solid var(--background-color);
  box-shadow: var(--shadow-light);
}

.timeline-date {
  margin: 0 0 var(--spacing-sm) 0;
  font-weight: 600;
  color: var(--primary-color);
}

.timeline-title {
  font-size: 1.25rem;
  margin-bottom: var(--spacing-sm);
}

.timeline-description {
  color: var(--text-light);
  line-height: 1.6;
}

/* Footer */
.footer {
  background: var(--text-color);
  color: white;
  padding: var(--spacing-2xl) 0;
  text-align: center;
}

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

.footer-section h4 {
  color: white;
  margin-bottom: var(--spacing-md);
}

.footer-section a {
  color: #d1d5db;
  display: block;
  margin-bottom: var(--spacing-sm);
}

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

.footer-bottom {
  border-top: 1px solid #374151;
  padding-top: var(--spacing-lg);
  color: #9ca3af;
}

/* Responsive Design */
@media (max-width: 768px) {
  .mobile-menu-toggle {
    display: block;
  }
  
  .nav-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--background-color);
    box-shadow: var(--shadow-medium);
    flex-direction: column;
    padding: var(--spacing-lg);
    gap: var(--spacing-md);
  }
  
  .nav-menu.active {
    display: flex;
  }
  
  .hero-title {
    font-size: 2.5rem;
  }
  
  .content-grid {
    grid-template-columns: 1fr;
    gap: var(--spacing-xl);
  }
  
  .sidebar {
    position: static;
    order: -1;
  }
  
  .btn-group {
    flex-direction: column;
    align-items: center;
  }
  
  .btn {
    width: 100%;
    max-width: 300px;
    text-align: center;
  }
  
  h1 {
    font-size: 2rem;
  }
  
  h2 {
    font-size: 1.75rem;
  }
  
  .container {
    padding: 0 var(--spacing-sm);
  }
  
  .section {
    padding: var(--spacing-2xl) 0;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 2rem;
  }
  
  .hero-image {
    width: 150px;
    height: 150px;
  }
  
  .publication-links {
    flex-direction: column;
  }
  
  .timeline {
    padding-left: var(--spacing-md);
  }
  
  .timeline-item {
    padding-left: var(--spacing-md);
  }
}

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

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

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

.animate-fade-in {
  animation: fadeIn 0.6s ease-out;
}

/* Utility Classes */
.text-center {
  text-align: center;
}

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

.text-right {
  text-align: right;
}

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: var(--spacing-xs); }
.mb-2 { margin-bottom: var(--spacing-sm); }
.mb-3 { margin-bottom: var(--spacing-md); }
.mb-4 { margin-bottom: var(--spacing-lg); }
.mb-5 { margin-bottom: var(--spacing-xl); }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: var(--spacing-xs); }
.mt-2 { margin-top: var(--spacing-sm); }
.mt-3 { margin-top: var(--spacing-md); }
.mt-4 { margin-top: var(--spacing-lg); }
.mt-5 { margin-top: var(--spacing-xl); }

.hidden {
  display: none;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}