/* ==================== CSS Variables ==================== */
:root {
  /* Colors - Dark Mode */
  --bg-primary: #0b1020;
  --bg-secondary: #0f172a;
  --bg-tertiary: #1e293b;
  --text-primary: #e5e7eb;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --brand-primary: #38bdf8;
  --brand-secondary: #22d3ee;
  --accent: #818cf8;
  --border-color: rgba(148, 163, 184, 0.2);
  --shadow-sm: 0 2px 8px rgba(2, 6, 23, 0.15);
  --shadow-md: 0 8px 24px rgba(2, 6, 23, 0.25);
  --shadow-lg: 0 16px 40px rgba(2, 6, 23, 0.35);
  --ring: rgba(56, 189, 248, 0.35);
  --success: #10b981;
  --warning: #f59e0b;
  
  /* Spacing */
  --spacing-xs: 8px;
  --spacing-sm: 12px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  --spacing-2xl: 48px;
  
  /* Border Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --radius-full: 9999px;
  
  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.2s ease;
  --transition-slow: 0.3s ease;
}

/* Light Mode */
@media (prefers-color-scheme: light) {
  :root {
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-tertiary: #f1f5f9;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #64748b;
    --brand-primary: #0284c7;
    --brand-secondary: #0891b2;
    --accent: #6366f1;
    --border-color: rgba(148, 163, 184, 0.3);
    --shadow-sm: 0 2px 8px rgba(15, 23, 42, 0.08);
    --shadow-md: 0 8px 24px rgba(15, 23, 42, 0.12);
    --shadow-lg: 0 16px 40px rgba(15, 23, 42, 0.15);
    --ring: rgba(2, 132, 199, 0.25);
  }
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: ui-sans-serif, system-ui, -apple-system, 'Segoe UI', Roboto, 
    'Helvetica Neue', Arial, 'Noto Sans', sans-serif, 'Apple Color Emoji', 
    'Segoe UI Emoji';
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ==================== Typography ==================== */
h1, h2, h3, h4, h5, h6 {
  line-height: 1.3;
  font-weight: 700;
}

h1 {
  font-size: clamp(28px, 4vw, 42px);
  margin-bottom: var(--spacing-sm);
}

h2 {
  font-size: clamp(24px, 3vw, 32px);
  margin-bottom: var(--spacing-md);
}

h3 {
  font-size: clamp(18px, 2.5vw, 24px);
  margin-bottom: var(--spacing-sm);
}

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

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

a:hover {
  color: var(--brand-secondary);
}

/* ==================== Layout ==================== */
.wrapper {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--spacing-lg);
}

/* ==================== Header ==================== */
header {
  display: flex;
  align-items: center;
  gap: var(--spacing-xl);
  background: linear-gradient(
    145deg,
    rgba(56, 189, 248, 0.08),
    rgba(34, 211, 238, 0.05)
  );
  border: 1px solid var(--ring);
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  margin-bottom: var(--spacing-xl);
  box-shadow: var(--shadow-lg);
  animation: fadeInDown 0.6s ease;
}

.avatar {
  width: 140px;
  height: 140px;
  border-radius: var(--radius-lg);
  object-fit: cover;
  border: 3px solid var(--ring);
  box-shadow: var(--shadow-md);
  transition: transform var(--transition-base);
}

.avatar:hover {
  transform: scale(1.05);
}

.header-content {
  flex: 1;
}

.subtitle {
  color: var(--text-secondary);
  font-size: 1.1rem;
  margin-bottom: var(--spacing-md);
}

.muted {
  color: var(--text-muted);
  font-weight: 400;
}

.badges {
  display: flex;
  gap: var(--spacing-sm);
  flex-wrap: wrap;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--bg-secondary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  padding: 8px 14px;
  border-radius: var(--radius-full);
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition-base);
  white-space: nowrap;
}

.badge:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
  border-color: var(--brand-primary);
}

.icon {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
}

/* ==================== Navigation ==================== */
.nav-bar {
  display: flex;
  gap: var(--spacing-md);
  flex-wrap: wrap;
  margin-bottom: var(--spacing-xl);
  padding: var(--spacing-md);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  position: sticky;
  top: var(--spacing-md);
  z-index: 100;
  backdrop-filter: blur(10px);
  animation: fadeIn 0.8s ease;
}

.nav-bar a {
  padding: 8px 16px;
  border-radius: var(--radius-md);
  font-weight: 600;
  transition: all var(--transition-base);
}

.nav-bar a:hover {
  background: linear-gradient(
    135deg,
    rgba(56, 189, 248, 0.15),
    rgba(34, 211, 238, 0.1)
  );
}

/* ==================== Sections ==================== */
.content-section {
  margin: var(--spacing-2xl) 0;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  animation: fadeInUp 0.6s ease;
}

.section-title {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-lg);
  padding-bottom: var(--spacing-md);
  border-bottom: 2px solid var(--border-color);
}

.title-icon {
  font-size: 1.8rem;
}

/* ==================== About Section ==================== */
.about-content p {
  font-size: 1.05rem;
  line-height: 1.8;
}

.info-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-md);
  margin-top: var(--spacing-lg);
}

.info-card {
  background: var(--bg-tertiary);
  border: 1px dashed var(--border-color);
  border-radius: var(--radius-md);
  padding: var(--spacing-md);
  transition: all var(--transition-base);
}

.info-card:hover {
  border-color: var(--brand-primary);
  transform: translateY(-2px);
}

.info-label {
  color: var(--text-muted);
  font-size: 0.85rem;
  margin-bottom: 4px;
}

.info-value {
  font-weight: 600;
  font-size: 1.05rem;
}

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

.timeline::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(
    to bottom,
    var(--brand-primary),
    var(--brand-secondary)
  );
}

.timeline-item {
  position: relative;
  margin-bottom: var(--spacing-xl);
}

.timeline-marker {
  position: absolute;
  left: -42px;
  top: 8px;
  width: 12px;
  height: 12px;
  background: var(--brand-primary);
  border: 3px solid var(--bg-secondary);
  border-radius: 50%;
  box-shadow: 0 0 0 4px var(--ring);
}

.timeline-content {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  transition: all var(--transition-base);
}

.timeline-content:hover {
  transform: translateX(8px);
  box-shadow: var(--shadow-md);
}

.timeline-date {
  color: var(--text-muted);
  font-family: ui-monospace, monospace;
  font-size: 0.9rem;
  margin-bottom: var(--spacing-sm);
}

.timeline-content h3 {
  color: var(--brand-primary);
  margin-bottom: var(--spacing-sm);
}

.institution,
.major,
.advisor,
.achievement,
.description {
  margin-top: 6px;
  color: var(--text-secondary);
}

.achievement {
  color: var(--success);
  font-weight: 500;
}

/* ==================== Research Section ==================== */
.research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-lg);
}

.research-card {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  transition: all var(--transition-base);
}

.research-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--brand-primary);
}

.research-icon {
  font-size: 2.5rem;
  margin-bottom: var(--spacing-md);
}

.research-card h3 {
  color: var(--brand-primary);
  margin-bottom: var(--spacing-sm);
}

.research-card p {
  color: var(--text-secondary);
  margin-bottom: 0;
}

/* ==================== Publications Section ==================== */
.publications {
  max-width: 100%;
}

.year-divider {
  color: var(--brand-primary);
  font-size: 1.3rem;
  margin: var(--spacing-lg) 0 var(--spacing-md) 0;
  padding-bottom: var(--spacing-sm);
  border-bottom: 1px solid var(--border-color);
}

.publication-item {
  margin-bottom: var(--spacing-lg);
  padding: var(--spacing-lg);
  background: var(--bg-tertiary);
  border-left: 3px solid var(--brand-primary);
  border-radius: var(--radius-md);
  transition: all var(--transition-base);
}

.publication-item:hover {
  background: var(--bg-secondary);
  box-shadow: var(--shadow-sm);
  transform: translateX(4px);
}

.pub-title {
  font-size: 1.05rem;
  line-height: 1.6;
  margin-bottom: var(--spacing-sm);
}

.pub-venue {
  color: var(--text-secondary);
  margin-bottom: var(--spacing-sm);
}

.pub-links {
  display: flex;
  gap: var(--spacing-md);
  align-items: center;
  flex-wrap: wrap;
}

.pub-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  font-size: 0.9rem;
  transition: all var(--transition-base);
}

.pub-link:hover {
  background: var(--brand-primary);
  color: white;
  transform: translateY(-2px);
}

.pub-award {
  padding: 6px 12px;
  background: linear-gradient(135deg, #f59e0b, #d97706);
  color: white;
  border-radius: var(--radius-md);
  font-size: 0.85rem;
  font-weight: 600;
}

/* ==================== Projects Section ==================== */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: var(--spacing-lg);
}

.project-card {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  transition: all var(--transition-base);
}

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

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

.project-status {
  padding: 4px 10px;
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  font-weight: 600;
}

.project-status.active {
  background: rgba(16, 185, 129, 0.2);
  color: var(--success);
}

.project-status.completed {
  background: rgba(56, 189, 248, 0.2);
  color: var(--brand-primary);
}

.project-desc {
  color: var(--text-secondary);
  margin-bottom: var(--spacing-md);
}

.project-tech {
  display: flex;
  gap: var(--spacing-xs);
  flex-wrap: wrap;
}

.tech-tag {
  padding: 4px 10px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  color: var(--text-secondary);
}

/* ==================== Awards Section ==================== */
.awards-list {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
}

.award-item {
  display: flex;
  gap: var(--spacing-lg);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  transition: all var(--transition-base);
}

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

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

.award-image img {
  width: 200px;
  height: auto;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
}

.award-content h3 {
  color: var(--brand-primary);
  margin-bottom: var(--spacing-sm);
}

.award-org {
  color: var(--text-secondary);
  font-weight: 600;
  margin-bottom: var(--spacing-xs);
}

.award-desc {
  color: var(--text-secondary);
  margin-bottom: var(--spacing-xs);
}

.award-date {
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* ==================== Service Section ==================== */
.service-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-lg);
}

.service-category {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
}

.service-category h3 {
  color: var(--brand-primary);
  margin-bottom: var(--spacing-md);
}

.service-category ul {
  list-style: none;
  padding: 0;
}

.service-category li {
  padding: var(--spacing-sm);
  margin-bottom: var(--spacing-xs);
  color: var(--text-secondary);
  border-left: 2px solid var(--brand-primary);
  padding-left: var(--spacing-md);
}

/* ==================== Footer ==================== */
footer {
  margin-top: var(--spacing-2xl);
  padding: var(--spacing-xl) 0;
  text-align: center;
  border-top: 1px solid var(--border-color);
}

.footer-content {
  color: var(--text-muted);
}

.footer-note {
  font-size: 0.9rem;
  margin-top: var(--spacing-sm);
}

/* ==================== Animations ==================== */
@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeInDown {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ==================== Responsive Design ==================== */
@media (max-width: 768px) {
  header {
    flex-direction: column;
    text-align: center;
  }
  
  .avatar {
    width: 120px;
    height: 120px;
  }
  
  .nav-bar {
    position: static;
    justify-content: center;
  }
  
  .timeline {
    padding-left: var(--spacing-lg);
  }
  
  .timeline-marker {
    left: -32px;
  }
  
  .award-item {
    flex-direction: column;
  }
  
  .award-image img {
    width: 100%;
    max-width: 300px;
  }
  
  .wrapper {
    padding: var(--spacing-md);
  }
}

@media (max-width: 480px) {
  .nav-bar {
    flex-direction: column;
    align-items: stretch;
  }
  
  .nav-bar a {
    text-align: center;
  }
  
  .info-cards {
    grid-template-columns: 1fr;
  }
  
  .research-grid,
  .projects-grid {
    grid-template-columns: 1fr;
  }
}

/* ==================== Utilities ==================== */
.text-center {
  text-align: center;
}

.mt-sm {
  margin-top: var(--spacing-sm);
}

.mt-md {
  margin-top: var(--spacing-md);
}

.mt-lg {
  margin-top: var(--spacing-lg);
}

.mb-sm {
  margin-bottom: var(--spacing-sm);
}

.mb-md {
  margin-bottom: var(--spacing-md);
}

.mb-lg {
  margin-bottom: var(--spacing-lg);
}