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

:root {
  /* Light theme colors */
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --text-primary: #0f172a;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --border-color: #e2e8f0;
  --accent-primary: #3b82f6;
  --accent-secondary: #1e40af;
  --card-bg: #ffffff;
  --nav-bg: rgba(255, 255, 255, 0.95);

  /* Gradients */
  --gradient-blue: linear-gradient(135deg, #dbeafe 0%, #bfdbfe 100%);
  --gradient-green: linear-gradient(135deg, #dcfce7 0%, #bbf7d0 100%);
  --gradient-purple: linear-gradient(135deg, #fae8ff 0%, #f3e8ff 100%);

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);

  /* Transitions */
  --transition: all 0.3s ease;
}

[data-theme="dark"] {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --border-color: #334155;
  --accent-primary: #60a5fa;
  --accent-secondary: #3b82f6;
  --card-bg: #1e293b;
  --nav-bg: rgba(15, 23, 42, 0.95);

  --gradient-blue: linear-gradient(135deg, #1e3a8a 0%, #1e40af 100%);
  --gradient-green: linear-gradient(135deg, #166534 0%, #15803d 100%);
  --gradient-purple: linear-gradient(135deg, #7c2d12 0%, #9333ea 100%);
}

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

/* Navigation */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: var(--nav-bg);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  transition: var(--transition);
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4rem;
}

.nav-brand a {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  transition: var(--transition);
}

.nav-brand a:hover {
  color: var(--accent-primary);
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.875rem;
  transition: var(--transition);
  position: relative;
}

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

.nav-link.active::after {
  content: "";
  position: absolute;
  bottom: -0.5rem;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--accent-primary);
  border-radius: 1px;
}

.theme-toggle {
  background: none;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 0.5rem;
  border-radius: 0.375rem;
  transition: var(--transition);
  position: relative;
  width: 2.5rem;
  height: 2.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.theme-toggle:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

.theme-toggle .sun-icon {
  transition: var(--transition);
}

.theme-toggle .moon-icon {
  position: absolute;
  transition: var(--transition);
  opacity: 0;
  transform: rotate(90deg) scale(0);
}

[data-theme="dark"] .theme-toggle .sun-icon {
  opacity: 0;
  transform: rotate(-90deg) scale(0);
}

[data-theme="dark"] .theme-toggle .moon-icon {
  opacity: 1;
  transform: rotate(0deg) scale(1);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 0.5rem;
  border-radius: 0.375rem;
  transition: var(--transition);
}

.nav-toggle:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
}

/* Sections */
.section {
  display: none;
  min-height: 100vh;
  padding: 6rem 0 2rem;
}

.section.active {
  display: block;
}

.section-header {
  text-align: center;
  margin-bottom: 3rem;
}

.page-title {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

.page-description {
  font-size: 1.125rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

.section-title {
  font-size: 2rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 1.5rem;
}

/* Cards */
.card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  box-shadow: var(--shadow-sm);
  margin-bottom: 2rem;
  transition: var(--transition);
}

.card:hover {
  box-shadow: var(--shadow-md);
}

.card-content {
  padding: 2rem;
}

/* Home Section */
.hero-grid {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 3rem;
  align-items: center;
  margin-bottom: 3rem;
}

.hero-content {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.hero-title {
  font-size: 3rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.1;
  margin-bottom: 0.5rem;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

.hero-description {
  font-size: 1.125rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.hero-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

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

.profile-image {
  width: 280px;
  height: 350px;
  object-fit: cover;
  border-radius: 0.75rem;
  box-shadow: var(--shadow-lg);
}

.about-text p {
  margin-bottom: 1rem;
  color: var(--text-secondary);
  font-size: 1rem;
  line-height: 1.7;
}

.research-item {
  margin-bottom: 2rem;
}

.research-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
}

.research-description {
  color: var(--text-secondary);
  margin-bottom: 1rem;
  line-height: 1.6;
}

.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
}

.skill-category {
  margin-bottom: 1.5rem;
}

.skill-title {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 1rem;
  border-radius: 0.375rem;
  font-weight: 500;
  font-size: 0.875rem;
  text-decoration: none;
  transition: var(--transition);
  cursor: pointer;
  border: none;
}

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

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

.btn-outline {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
}

.btn-outline:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border-color: var(--accent-primary);
}

/* Tags */
.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  background: var(--bg-tertiary);
  color: var(--text-primary);
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 500;
}

.tag-outline {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 500;
}

/* Experience Section */
.experience-timeline {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.experience-card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-left: 4px solid var(--accent-primary);
  border-radius: 0.75rem;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.experience-card:hover {
  box-shadow: var(--shadow-md);
}

.experience-card.education {
  border-left-color: #3b82f6;
}

.experience-header {
  padding: 1.5rem 1.5rem 0;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
}

.experience-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.experience-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.experience-meta span {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.experience-type {
  background: var(--accent-primary);
  color: white;
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 500;
}

.experience-type.internship {
  background: var(--text-secondary);
}

.experience-content {
  padding: 0 1.5rem 1.5rem;
}

.experience-list {
  list-style: none;
  margin-bottom: 1.5rem;
}

.experience-list li {
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
  margin-bottom: 0.5rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.experience-list li::before {
  content: "";
  width: 6px;
  height: 6px;
  background: var(--accent-primary);
  border-radius: 50%;
  margin-top: 0.5rem;
  flex-shrink: 0;
}

.experience-skills h4 {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.education-description {
  color: var(--text-secondary);
  margin-bottom: 1rem;
  line-height: 1.6;
}

/* Publications Section */
.empty-state {
  text-align: center;
  padding: 3rem 2rem;
  background: var(--card-bg);
  border: 2px dashed var(--border-color);
  border-radius: 0.75rem;
  margin-bottom: 2rem;
}

.empty-icon {
  width: 4rem;
  height: 4rem;
  background: var(--bg-tertiary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 1rem;
  color: var(--text-muted);
}

.empty-content h3 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.empty-content p {
  color: var(--text-secondary);
  max-width: 400px;
  margin: 0 auto;
  line-height: 1.6;
}

.empty-meta {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-top: 1.5rem;
  color: var(--text-muted);
  font-size: 0.875rem;
}

.meta-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.upcoming-research {
  background: var(--bg-secondary);
  border-radius: 0.75rem;
  padding: 1.5rem;
  margin-bottom: 2rem;
}

.research-preview h3 {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
}

.research-preview p {
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
  line-height: 1.6;
}

.research-status {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Projects Section */
.filter-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 2rem;
  justify-content: center;
}

.filter-tab {
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 0.5rem 1rem;
  border-radius: 9999px;
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
}

.filter-tab:hover,
.filter-tab.active {
  background: var(--accent-primary);
  color: white;
  border-color: var(--accent-primary);
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
  gap: 1.5rem;
  margin-bottom: 3rem;
}

.project-card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-left: 4px solid var(--accent-primary);
  border-radius: 0.75rem;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
  overflow: hidden;
}

.project-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.project-header {
  padding: 1.5rem 1.5rem 0;
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
}

.project-icon {
  width: 3rem;
  height: 3rem;
  background: var(--bg-tertiary);
  border-radius: 0.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent-primary);
  flex-shrink: 0;
}

.project-info {
  flex: 1;
}

.project-title {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
  line-height: 1.4;
}

.project-category {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 500;
}

.project-content {
  padding: 1rem 1.5rem 1.5rem;
}

.project-description {
  color: var(--text-secondary);
  margin-bottom: 1rem;
  line-height: 1.6;
}

.project-features {
  margin-bottom: 1rem;
}

.project-features h4,
.project-tech h4 {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
  font-size: 0.875rem;
}

.project-features ul {
  list-style: none;
  margin-bottom: 1rem;
}

.project-features li {
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
  margin-bottom: 0.25rem;
  color: var(--text-secondary);
  font-size: 0.875rem;
  line-height: 1.5;
}

.project-features li::before {
  content: "";
  width: 4px;
  height: 4px;
  background: var(--accent-primary);
  border-radius: 50%;
  margin-top: 0.5rem;
  flex-shrink: 0;
}

.github-cta {
  text-align: center;
  background: var(--bg-secondary);
  border-radius: 0.75rem;
  padding: 2rem;
}

.cta-content h3 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

.cta-content p {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  line-height: 1.6;
}

/* News Section */
.news-timeline {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  margin-bottom: 3rem;
}

.news-item {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.news-item:hover {
  box-shadow: var(--shadow-md);
}

.news-header {
  padding: 1.5rem 1.5rem 0;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
}

.news-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.news-meta {
  display: flex;
  align-items: center;
  gap: 1rem;
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.news-date {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.news-category {
  background: var(--accent-primary);
  color: white;
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 500;
}

.news-category.career {
  background: #10b981;
}

.news-category.project {
  background: #f59e0b;
}

.news-category.education {
  background: #8b5cf6;
}

.news-content {
  padding: 0 1.5rem 1.5rem;
}

.news-content p {
  color: var(--text-secondary);
  margin-bottom: 1rem;
  line-height: 1.6;
}

.news-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

/* More Section */
.brainstorm-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
  margin-bottom: 3rem;
}

.brainstorm-card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.brainstorm-card:hover {
  box-shadow: var(--shadow-lg);
}

.brainstorm-header {
  padding: 1.5rem 1.5rem 0;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.brainstorm-icon {
  width: 2.5rem;
  height: 2.5rem;
  background: var(--accent-primary);
  background-attachment: 0.1;
  border-radius: 0.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent-primary);
}

.brainstorm-title {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
}

.brainstorm-content {
  padding: 0 1.5rem 1.5rem;
}

.brainstorm-content p {
  color: var(--text-secondary);
  margin-bottom: 1rem;
  line-height: 1.6;
}

.discussion-topics {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  padding: 1.5rem;
  margin-bottom: 3rem;
}

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

.topic-item {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  padding: 0.75rem;
  border-radius: 0.5rem;
  transition: var(--transition);
}

.topic-item:hover {
  background: var(--bg-secondary);
}

.topic-bullet {
  width: 8px;
  height: 8px;
  background: var(--accent-primary);
  border-radius: 50%;
  margin-top: 0.5rem;
  flex-shrink: 0;
}

.topic-item span:last-child {
  color: var(--text-secondary);
  font-size: 0.875rem;
  line-height: 1.5;
}

.collaboration-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1rem;
  margin-bottom: 3rem;
}

.collab-card {
  padding: 1.5rem;
  border-radius: 0.75rem;
  border: 1px solid var(--border-color);
}

.collab-card.blue {
  background: var(--gradient-blue);
}

.collab-card.green {
  background: var(--gradient-green);
}

.collab-card.purple {
  background: var(--gradient-purple);
}

.collab-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
}

.collab-header h3 {
  font-weight: 600;
  color: var(--text-primary);
}

.collab-card p {
  color: var(--text-secondary);
  font-size: 0.875rem;
  line-height: 1.6;
}

.contact-cta {
  background: var(--accent-primary);
  background-attachment: 0.05;
  border: 1px solid var(--accent-primary);
  border-spacing: 0.2;
  border-radius: 0.75rem;
  padding: 2rem;
  text-align: center;
}

.cta-icon {
  width: 4rem;
  height: 4rem;
  background: var(--accent-primary);
  background-attachment: 0.1;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 1rem;
  color: var(--accent-primary);
}

.contact-cta h3 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.contact-cta p {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  max-width: 400px;
  margin-left: auto;
  margin-right: auto;
  line-height: 1.6;
}

.cta-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
}

/* Responsive Design */
@media (max-width: 768px) {
  .nav-menu {
    position: fixed;
    top: 4rem;
    left: 0;
    right: 0;
    background: var(--nav-bg);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem;
    flex-direction: column;
    gap: 1rem;
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
  }

  .nav-menu.active {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }

  .nav-toggle {
    display: block;
  }

  .hero-grid {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .hero-title {
    font-size: 2.5rem;
  }

  .page-title {
    font-size: 2rem;
  }

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

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

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

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

  .collaboration-cards {
    grid-template-columns: 1fr;
  }

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

  .experience-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .experience-meta {
    flex-direction: column;
    gap: 0.5rem;
  }

  .news-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .filter-tabs {
    justify-content: flex-start;
    overflow-x: auto;
    padding-bottom: 0.5rem;
  }

  .filter-tab {
    white-space: nowrap;
  }

  .cta-buttons {
    flex-direction: column;
    align-items: center;
  }

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

@media (max-width: 480px) {
  .container {
    padding: 0 0.75rem;
  }

  .card-content {
    padding: 1.5rem;
  }

  .project-content {
    padding: 1rem 1.5rem 1.5rem;
  }

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

  .page-title {
    font-size: 1.75rem;
  }

  .profile-image {
    width: 240px;
    height: 300px;
  }

  .hero-buttons {
    flex-direction: column;
    align-items: stretch;
  }

  .btn {
    justify-content: center;
  }
}

/* Animations */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.section.active {
  animation: fadeIn 0.5s ease-out;
}

/* Scrollbar Styling */
::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
  background: var(--border-color);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* Focus States */
.btn:focus,
.nav-link:focus,
.theme-toggle:focus,
.filter-tab:focus {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

/* Print Styles */
@media print {
  .navbar,
  .theme-toggle,
  .nav-toggle {
    display: none;
  }

  .section {
    display: block !important;
    page-break-after: always;
  }

  .section:last-child {
    page-break-after: auto;
  }
}