:root {
  --bg: #ffffff;
  --card: #f8f9fa;
  --card-hover: #ffffff;
  --text: #000000;
  --text-secondary: #6c757d;
  --muted: #868e96;
  --accent: #2698ba;
  --border: #dee2e6;
  --shadow: rgba(0,0,0,0.1);
}

[data-theme="dark"] {
  --bg: #121212;
  --card: #1e1e1e;
  --card-hover: #2a2a2a;
  --text: #e0e0e0;
  --text-secondary: #b0b0b0;
  --muted: #7a7a7a;
  --accent: #38bdf8;
  --border: #2a2a2a;
  --shadow: rgba(0,0,0,0.4);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  transition: background 0.3s ease, color 0.3s ease;
}

/* Navigation */
.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 40px;
  position: sticky;
  top: 0;
  background: var(--bg);
  z-index: 1000;
  border-bottom: 1px solid var(--border);
}

.navbar .logo {
  color: var(--text);
  text-decoration: none;
  font-size: 1.1rem;
}

.navbar .logo strong {
  font-weight: 700;
}

.navbar ul {
  display: flex;
  list-style: none;
  gap: 30px;
  align-items: center;
}

.navbar a {
  color: var(--text);
  text-decoration: none;
  transition: color 0.2s;
}

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

.theme-toggle {
  background: none;
  border: none;
  color: var(--text);
  font-size: 1.1rem;
  cursor: pointer;
  padding: 8px;
  transition: color 0.2s;
}

.theme-toggle:hover {
  color: var(--accent);
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 40px 20px;
}

/* About Section */
.about-section {
  margin-bottom: 80px;
}

.profile-container {
  display: flex;
  gap: 40px;
  align-items: flex-start;
  margin-bottom: 40px;
}

.profile-image {
  flex-shrink: 0;
}

.profile-pic {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid var(--border);
}

.profile-content {
  flex: 1;
}

.profile-title {
  font-size: 2rem;
  margin-bottom: 8px;
  font-weight: 300;
}

.name-bold {
  font-weight: 700;
}

.profile-subtitle {
  color: var(--text-secondary);
  font-size: 1rem;
  margin-bottom: 16px;
}

.profile-description {
  margin-bottom: 20px;
  line-height: 1.7;
  color: var(--text-secondary);
}

.profile-interests {
  margin-bottom: 20px;
  padding: 12px;
  background: var(--card);
  border-left: 3px solid var(--accent);
  border-radius: 4px;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.profile-interests strong {
  color: var(--text);
}

.social-links {
  display: flex;
  gap: 15px;
  font-size: 1.5rem;
}

.social-links a {
  color: var(--text);
  transition: color 0.2s;
}

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

/* Section Titles */
.section-title {
  font-size: 1.5rem;
  font-weight: 500;
  margin-bottom: 24px;
  display: inline-block;
  color: var(--text);
  text-decoration: none;
  border-bottom: 2px solid transparent;
  transition: border-color 0.2s;
}

.section-title:hover {
  border-bottom-color: var(--accent);
}

h2 {
  margin-bottom: 24px;
}

/* Recent Paper Alert */
.recent-paper-section {
  margin-bottom: 60px;
}

.paper-alert {
  padding: 0;
  background: transparent;
}

.paper-link {
  display: block;
  margin-bottom: 24px;
}

.paper-image {
  width: 100%;
  max-width: 700px;
  height: auto;
  display: block;
}

.paper-info {
  margin-top: 24px;
  text-align: left;
}

.paper-alert-intro {
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--accent);
}

.paper-title {
  font-size: 1.1rem;
  font-weight: 500;
  margin-bottom: 8px;
  line-height: 1.6;
  color: var(--text);
}

.paper-title a {
  color: var(--text);
  text-decoration: none;
  transition: color 0.2s;
}

.paper-title a:hover {
  color: var(--accent);
}

.paper-journal {
  color: var(--muted);
  font-style: italic;
  font-weight: 400;
  font-size: 0.95rem;
}

/* Publications */
.publications-section {
  margin-bottom: 60px;
}

.year-header {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--accent);
  margin-top: 40px;
  margin-bottom: 20px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--border);
}

.year-header:first-child {
  margin-top: 0;
}

.publication-item {
  margin-bottom: 32px;
  padding: 20px;
  background: var(--card);
  border-radius: 8px;
  border: 1px solid var(--border);
  transition: transform 0.2s, box-shadow 0.2s;
}

.publication-item:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px var(--shadow);
  background: var(--card-hover);
}

.pub-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text);
}

.pub-authors {
  color: var(--text-secondary);
  margin-bottom: 6px;
  font-size: 0.95rem;
}

.author-me {
  font-weight: 600;
  color: var(--text);
}

.pub-venue {
  font-style: italic;
  color: var(--muted);
  margin-bottom: 10px;
  font-size: 0.9rem;
}

.pub-links {
  display: flex;
  gap: 12px;
  margin-bottom: 12px;
}

.pub-link {
  color: var(--accent);
  text-decoration: none;
  font-size: 0.9rem;
  transition: opacity 0.2s;
}

.pub-link:hover {
  opacity: 0.7;
}

.pub-abstract {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.6;
}

/* Skills Section */
.skills {
  margin-bottom: 60px;
}

.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 24px;
  margin-top: 24px;
}

.skill-category h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.skill-category h3 i {
  color: var(--accent);
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.tag {
  background: var(--card);
  color: var(--text);
  padding: 6px 12px;
  border-radius: 16px;
  font-size: 0.85rem;
  border: 1px solid var(--border);
  transition: background 0.2s;
}

.tag:hover {
  background: var(--accent);
  color: white;
  border-color: var(--accent);
}

/* Contact Section */
.contact {
  margin-bottom: 60px;
}

.contact-description {
  color: var(--text-secondary);
  margin-bottom: 20px;
}

.contact-info {
  margin-bottom: 20px;
}

.contact-info p {
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.contact-info i {
  color: var(--accent);
  width: 20px;
}

.contact-info a {
  color: var(--accent);
  text-decoration: none;
}

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

.social-links-contact {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.btn-contact {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  background: var(--card);
  color: var(--text);
  text-decoration: none;
  border-radius: 6px;
  border: 1px solid var(--border);
  transition: background 0.2s, border-color 0.2s;
}

.btn-contact:hover {
  background: var(--accent);
  color: white;
  border-color: var(--accent);
}

/* Projects Page */
.page-header {
  margin-bottom: 40px;
}

.page-header h1 {
  font-size: 2rem;
  font-weight: 500;
  margin-bottom: 8px;
}

.page-header p {
  color: var(--text-secondary);
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 24px;
  margin-top: 40px;
}

.project-card {
  background: var(--card);
  padding: 24px;
  border-radius: 8px;
  border: 1px solid var(--border);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.project-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px var(--shadow);
  background: var(--card-hover);
}

.project-card h3 {
  font-size: 1.2rem;
  margin-bottom: 12px;
  color: var(--text);
}

.project-card p {
  color: var(--text-secondary);
  margin-bottom: 16px;
  line-height: 1.6;
}

.project-links {
  display: flex;
  gap: 12px;
}

.project-links a {
  color: var(--accent);
  text-decoration: none;
  font-size: 0.9rem;
  transition: opacity 0.2s;
}

.project-links a:hover {
  opacity: 0.7;
}

/* Responsive Design */
@media (max-width: 768px) {
  .navbar {
    flex-direction: column;
    gap: 15px;
    padding: 15px 20px;
  }
  
  .navbar ul {
    gap: 15px;
  }
  
  .profile-container {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }
  
  .profile-pic {
    width: 150px;
    height: 150px;
  }
  
  .social-links {
    justify-content: center;
  }
  
  .skills-grid {
    grid-template-columns: 1fr;
  }
  
  .news-item {
    flex-direction: column;
    gap: 4px;
  }
  
  .projects-grid {
    grid-template-columns: 1fr;
  }
}