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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  line-height: 1.6;
  color: #333;
  background-color: #ffffff;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Header */
header {
  background: white;
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
  position: fixed;
  width: 100%;
  top: 0;
  z-index: 1000;
}

header .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 15px 20px;
}

.logo h1 {
  font-size: 1.5rem;
  font-weight: 600;
  color: #2c3e50;
  letter-spacing: 1px;
}

nav {
  display: flex;
  gap: 2rem;
}

nav a {
  text-decoration: none;
  color: #333;
  font-weight: 500;
  transition: color 0.3s ease;
  position: relative;
}

nav a:hover,
nav a.active {
  color: #3498db;
}

nav a::after {
  content: '';
  position: absolute;
  width: 0;
  height: 2px;
  bottom: -5px;
  left: 0;
  background-color: #3498db;
  transition: width 0.3s ease;
}

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

/* Hero section */
.hero {
  margin-top: 80px;
  padding: 80px 0;
  background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  min-height: 70vh;
  display: flex;
  align-items: center;
}

.hero-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
}

.hero-text h1 {
  font-size: 4rem;
  font-weight: 300;
  color: #2c3e50;
  line-height: 1.2;
  margin-bottom: 1rem;
}

.subtitle {
  font-size: 1.5rem;
  color: #7f8c8d;
  margin-bottom: 2rem;
  font-weight: 400;
}

.cta-button {
  display: inline-block;
  background: #2c3e50;
  color: white;
  padding: 15px 30px;
  text-decoration: none;
  font-weight: 500;
  border-radius: 5px;
  transition: background 0.3s ease;
}

.cta-button:hover {
  background: #34495e;
}

.hero-image {
  text-align: center;
}

.hero-image img {
  max-width: 100%;
  height: auto;
  border-radius: 10px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

/* Content sections */
.content {
  padding: 80px 0;
}

.content h2 {
  text-align: center;
  font-size: 2.5rem;
  color: #2c3e50;
  margin-bottom: 3rem;
  font-weight: 300;
}

.pdf-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.pdf-card {
  background: white;
  padding: 2rem;
  border-radius: 10px;
  box-shadow: 0 5px 15px rgba(0,0,0,0.1);
  transition: transform 0.3s ease;
}

.pdf-card:hover {
  transform: translateY(-5px);
}

.pdf-card h3 {
  color: #2c3e50;
  margin-bottom: 1rem;
  font-size: 1.5rem;
}

.pdf-card p {
  color: #7f8c8d;
  margin-bottom: 1.5rem;
}

.pdf-link {
  display: inline-block;
  color: #3498db;
  text-decoration: none;
  font-weight: 500;
  transition: color 0.3s ease;
}

.pdf-link:hover {
  color: #2980b9;
}

/* Page hero (for other pages) */
.page-hero {
  margin-top: 80px;
  padding: 60px 0;
  background: #f8f9fa;
  text-align: center;
}

.page-hero h1 {
  font-size: 3rem;
  color: #2c3e50;
  margin-bottom: 1rem;
  font-weight: 300;
}

.lead {
  font-size: 1.2rem;
  color: #7f8c8d;
}

/* Research page specific styles */
.research-nav {
  padding: 20px 0;
  background: #f8f9fa;
  border-bottom: 1px solid #dee2e6;
}

.research-tabs {
  display: flex;
  gap: 10px;
  justify-content: center;
  flex-wrap: wrap;
}

.tab-btn {
  background: white;
  border: 2px solid #dee2e6;
  padding: 10px 20px;
  border-radius: 5px;
  cursor: pointer;
  font-weight: 500;
  transition: all 0.3s ease;
  color: #333;
}

.tab-btn:hover {
  background: #f8f9fa;
  border-color: #3498db;
}

.tab-btn.active {
  background: #3498db;
  color: white;
  border-color: #3498db;
}

.research-content {
  padding: 40px 0;
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

.research-category {
  margin-bottom: 3rem;
}

.paper {
  margin-bottom: 2rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid #eee;
}

.paper:last-child {
  border-bottom: none;
}

.paper h4 {
  color: #2c3e50;
  margin-bottom: 0.5rem;
  font-size: 1.3rem;
}

.paper-subtitle {
  color: #7f8c8d;
  font-style: italic;
  margin-bottom: 1rem;
}

.read-paper-btn {
  display: inline-block;
  background: #2c3e50;
  color: white;
  padding: 8px 16px;
  text-decoration: none;
  border-radius: 5px;
  font-size: 0.9rem;
  margin-top: 1rem;
  transition: background 0.3s ease;
}

.read-paper-btn:hover {
  background: #34495e;
}

/* About page specific styles */
.about-main {
  padding: 60px 0;
}

.about-grid {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 3rem;
  align-items: start;
  margin-bottom: 4rem;
}

.about-text {
  font-size: 1.1rem;
  line-height: 1.8;
}

.about-text a {
  color: #3498db;
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s ease;
}

.about-text a:hover {
  border-bottom-color: #3498db;
}

.about-image img {
  width: 100%;
  max-width: 300px;
  height: auto;
  border-radius: 10px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

.education-section {
  border-top: 1px solid #eee;
  padding-top: 2rem;
}

.education-item {
  margin-bottom: 3rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid #f0f0f0;
}

.education-item:last-of-type {
  border-bottom: none;
}

.education-item h3 {
  color: #3498db;
  margin-bottom: 0.5rem;
  font-size: 1.2rem;
}

.education-item p {
  margin-bottom: 0.5rem;
  color: #333;
}

.education-item ul {
  margin-left: 1.5rem;
  margin-top: 0.5rem;
}

.education-item li {
  margin-bottom: 0.3rem;
}

.cv-button-container {
  text-align: center;
  margin-top: 2rem;
}

.view-cv-btn {
  display: inline-block;
  background: #2c3e50;
  color: white;
  padding: 12px 24px;
  text-decoration: none;
  font-weight: 500;
  border-radius: 5px;
  transition: background 0.3s ease;
}

.view-cv-btn:hover {
  background: #34495e;
}

/* Contact page styles - UPDATED */
.contact-hero {
  margin-top: 80px;
  padding: 60px 0;
  min-height: 70vh;
  display: flex;
  align-items: center;
  background: #ffffff;
}

.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
}

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

.contact-info h1 {
  font-size: 3rem;
  color: #2c3e50;
  margin-bottom: 2rem;
  font-weight: 300;
}

.contact-details {
  margin-bottom: 3rem;
  font-size: 1.1rem;
  line-height: 1.8;
}

.contact-details a {
  color: #3498db;
  text-decoration: none;
}

.contact-details a:hover {
  text-decoration: underline;
}

.profile-buttons {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  align-items: flex-start;
}

.profile-btn {
  display: inline-block;
  background: #2c3e50;
  color: white;
  padding: 12px 24px;
  text-decoration: none;
  font-weight: 500;
  border-radius: 5px;
  transition: background 0.3s ease;
  min-width: 250px;
  text-align: center;
}

.profile-btn:hover {
  background: #34495e;
}

.contact-image {
  height: 400px;
  overflow: hidden;
  border-radius: 10px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

.contact-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
}

/* CV page styles */
.cv-content {
  padding: 40px 0;
}

.cv-embed {
  margin-bottom: 2rem;
  text-align: center;
}

.cv-embed iframe {
  border: 1px solid #ddd;
  border-radius: 5px;
}

.cv-download {
  text-align: center;
}

.download-btn {
  display: inline-block;
  background: #3498db;
  color: white;
  padding: 12px 24px;
  text-decoration: none;
  font-weight: 500;
  border-radius: 5px;
  transition: background 0.3s ease;
}

.download-btn:hover {
  background: #2980b9;
}

/* Teaching page styles */
.teaching-content {
  padding: 60px 0;
}

.institution {
  margin-bottom: 4rem;
}

.institution h2 {
  color: #2c3e50;
  font-size: 2rem;
  margin-bottom: 2rem;
  font-weight: 400;
}

.course-section {
  margin-bottom: 3rem;
}

.course-section h3 {
  color: #333;
  font-size: 1.3rem;
  margin-bottom: 1rem;
  font-weight: 500;
}

.course-list {
  margin-left: 1rem;
}

.course {
  display: flex;
  justify-content: space-between;
  padding: 0.5rem 0;
  border-bottom: 1px solid #f0f0f0;
}

.course:last-child {
  border-bottom: none;
}

.course-name {
  font-weight: 500;
  color: #2c3e50;
}

.semester {
  color: #7f8c8d;
}

/* Footer */
footer {
  background: #2c3e50;
  color: white;
  text-align: center;
  padding: 40px 0;
  margin-top: 80px;
}

/* Responsive design */
@media (max-width: 768px) {
  .hero-content {
    grid-template-columns: 1fr;
    text-align: center;
  }
  
  .hero-text h1 {
    font-size: 2.5rem;
  }
  
  .subtitle {
    font-size: 1.2rem;
  }
  
  nav {
    gap: 1rem;
  }
  
  nav a {
    font-size: 0.9rem;
  }
  
  .logo h1 {
    font-size: 1.2rem;
  }
  
  .pdf-grid {
    grid-template-columns: 1fr;
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .research-tabs {
    flex-direction: column;
    align-items: center;
  }

  .course {
    flex-direction: column;
    gap: 0.25rem;
  }

  .contact-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
  
  .contact-image {
    height: 250px;
  }
  
  .contact-info h1 {
    font-size: 2.5rem;
  }
}

@media (max-width: 480px) {
  header .container {
    flex-direction: column;
    gap: 1rem;
  }
  
  .hero {
    margin-top: 120px;
    padding: 40px 0;
  }
  
  .hero-text h1 {
    font-size: 2rem;
  }
}