/* ====================================
   Modern Portfolio - Design System
   ==================================== */

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

/* CSS Variables */
:root {
  /* Colors - Dark Theme */
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-card: #1e293b;
  --bg-card-hover: #334155;

  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  --accent-primary: #3b82f6;
  --accent-secondary: #8b5cf6;
  --accent-gradient: linear-gradient(135deg, #3b82f6 0%, #8b5cf6 100%);

  --border-color: #334155;
  --success: #22c55e;
  --warning: #f59e0b;

  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --font-size-5xl: 3rem;

  /* Spacing */
  --spacing-1: 0.25rem;
  --spacing-2: 0.5rem;
  --spacing-3: 0.75rem;
  --spacing-4: 1rem;
  --spacing-6: 1.5rem;
  --spacing-8: 2rem;
  --spacing-12: 3rem;
  --spacing-16: 4rem;

  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;

  /* 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);
  --shadow-glow: 0 0 20px rgba(59, 130, 246, 0.3);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease;
  --transition-slow: 300ms ease;
}

/* Reset & Base */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg-primary);
  min-height: 100vh;
}

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

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

/* Layout */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-6);
}

/* Navigation */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(15, 23, 42, 0.7);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  padding: var(--spacing-4) 0;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-6);
}

.nav-brand {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--text-primary);
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav-links {
  display: flex;
  gap: var(--spacing-8);
  list-style: none;
}

.nav-links a {
  color: var(--text-secondary);
  font-weight: 500;
  transition: color var(--transition-fast);
}

.nav-links a:hover {
  color: var(--text-primary);
}

/* Hero Section */
.hero {
  padding: calc(80px + var(--spacing-16)) 0 var(--spacing-16);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 600px;
  background: radial-gradient(ellipse, rgba(59, 130, 246, 0.15) 0%, transparent 70%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
}

.hero h1 {
  font-size: var(--font-size-5xl);
  font-weight: 700;
  margin-bottom: var(--spacing-4);
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-title {
  font-size: var(--font-size-xl);
  color: var(--text-secondary);
  margin-bottom: var(--spacing-6);
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: var(--spacing-8);
  flex-wrap: wrap;
}

.stat {
  text-align: center;
}

.stat-value {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  color: var(--accent-primary);
}

.stat-label {
  font-size: var(--font-size-sm);
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Main Content */
.main {
  padding: var(--spacing-12) 0;
}

.content-grid {
  display: grid;
  grid-template-columns: 1fr 380px;
  gap: var(--spacing-8);
}

/* Section Headings */
.section-header {
  display: flex;
  align-items: center;
  gap: var(--spacing-4);
  margin-bottom: var(--spacing-6);
}

.section-title {
  font-size: var(--font-size-2xl);
  font-weight: 600;
}

.section-link {
  font-size: var(--font-size-sm);
  color: var(--text-muted);
}

/* Bio Card */
.bio-card {
  background: rgba(30, 41, 59, 0.6);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid transparent;
  border-radius: var(--radius-xl);
  padding: var(--spacing-8);
  margin-bottom: var(--spacing-8);
  position: relative;
  background-clip: padding-box;
}

.bio-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: var(--radius-xl);
  padding: 1px;
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.5), rgba(139, 92, 246, 0.5));
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
}

.bio-text {
  font-size: var(--font-size-lg);
  color: var(--text-secondary);
  line-height: 1.8;
}

.bio-links {
  margin-top: var(--spacing-6);
  display: flex;
  gap: var(--spacing-4);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-2);
  padding: var(--spacing-3) var(--spacing-6);
  border-radius: var(--radius-full);
  font-weight: 500;
  font-size: var(--font-size-sm);
  transition: all var(--transition-base);
  border: none;
  cursor: pointer;
}

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

.btn-primary:hover {
  box-shadow: var(--shadow-glow);
  transform: translateY(-2px);
  color: white;
}

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

.btn-secondary:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
}

/* News Sidebar */
.news-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: var(--spacing-6);
  position: sticky;
  top: 100px;
}

.news-title {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--spacing-4);
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
}

.news-list {
  list-style: none;
}

.news-item {
  padding: var(--spacing-4) 0;
  border-bottom: 1px solid var(--border-color);
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  line-height: 1.5;
}

.news-item:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.news-date {
  color: var(--accent-primary);
  font-weight: 600;
}

/* News Toggle */
.news-hidden {
  display: none;
  opacity: 0;
}

.news-hidden.show {
  display: list-item;
  opacity: 1;
  animation: fadeIn 0.3s ease forwards;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.news-toggle {
  width: 100%;
  padding: var(--spacing-3) var(--spacing-4);
  margin-top: var(--spacing-4);
  background: transparent;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.news-toggle:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
  border-color: var(--accent-primary);
}

/* Publications */
.publications-section {
  margin-top: var(--spacing-12);
}

.pub-filters {
  display: flex;
  gap: var(--spacing-2);
  margin-bottom: var(--spacing-6);
  flex-wrap: wrap;
}

.filter-btn {
  padding: var(--spacing-2) var(--spacing-4);
  border-radius: var(--radius-full);
  font-size: var(--font-size-sm);
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

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

.pub-grid {
  display: grid;
  gap: var(--spacing-4);
}

.pub-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--spacing-6);
  transition: all var(--transition-base);
}

.pub-card:hover {
  border-color: var(--accent-primary);
  transform: translateY(-4px);
  box-shadow: 0 0 30px rgba(59, 130, 246, 0.2), 0 0 60px rgba(139, 92, 246, 0.1);
}

.pub-header {
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-4);
  margin-bottom: var(--spacing-3);
}

.pub-number {
  font-size: var(--font-size-sm);
  color: var(--text-muted);
  min-width: 30px;
}

.pub-badge {
  font-size: var(--font-size-xs);
  padding: var(--spacing-1) var(--spacing-2);
  border-radius: var(--radius-sm);
  font-weight: 500;
  text-transform: uppercase;
}

.pub-badge.conference {
  background: #1d4ed8;
  color: white;
}

.pub-badge.journal {
  background: #7c3aed;
  color: white;
}

.pub-badge.arxiv {
  background: #059669;
  color: white;
}

.pub-badge.workshop {
  background: #d97706;
  color: white;
}

.pub-badge.poster {
  background: #dc2626;
  color: white;
}

.pub-badge.thesis {
  background: #be185d;
  color: white;
}

.pub-year {
  font-size: var(--font-size-sm);
  color: var(--text-muted);
  margin-left: auto;
}

.pub-title {
  font-size: var(--font-size-base);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-2);
}

.pub-authors {
  font-size: var(--font-size-sm);
  color: var(--text-muted);
  font-style: italic;
  margin-bottom: var(--spacing-2);
}

.pub-venue {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
}

.pub-links {
  margin-top: var(--spacing-3);
  display: flex;
  gap: var(--spacing-3);
}

.pub-award {
  margin-top: var(--spacing-2);
  font-size: var(--font-size-sm);
  color: var(--success);
  font-weight: 500;
}

/* Footer */
.footer {
  border-top: 1px solid var(--border-color);
  padding: var(--spacing-8) 0;
  margin-top: var(--spacing-16);
  text-align: center;
  color: var(--text-muted);
  font-size: var(--font-size-sm);
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--spacing-6);
  margin-bottom: var(--spacing-4);
}

/* Responsive */
@media (max-width: 900px) {
  .content-grid {
    grid-template-columns: 1fr;
  }

  .news-card {
    position: static;
  }

  .hero h1 {
    font-size: var(--font-size-4xl);
  }

  .hero-stats {
    gap: var(--spacing-6);
  }
}

@media (max-width: 600px) {
  .nav-links {
    display: none;
  }

  .hero h1 {
    font-size: var(--font-size-3xl);
  }

  .hero-title {
    font-size: var(--font-size-base);
  }

  .stat-value {
    font-size: var(--font-size-2xl);
  }

  .bio-card,
  .news-card,
  .pub-card {
    padding: var(--spacing-4);
  }

  .container {
    padding: 0 var(--spacing-4);
  }
}

/* ====================================
   Animations & Enhancements
   ==================================== */

/* Fade in on scroll */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Stat counter animation */
.stat-value {
  display: inline-block;
}

/* Back to Top Button */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background: var(--accent-gradient);
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-base);
  box-shadow: var(--shadow-lg);
  z-index: 99;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-glow);
}

.back-to-top svg {
  width: 24px;
  height: 24px;
  fill: white;
}

/* Nav Social Icons */
.nav-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  transition: all var(--transition-fast);
}

.nav-icon:hover {
  background: var(--bg-card-hover);
}

.nav-icon svg {
  width: 18px;
  height: 18px;
  fill: var(--text-secondary);
  transition: fill var(--transition-fast);
}

.nav-icon:hover svg {
  fill: var(--text-primary);
}

/* Section Divider */
.section-divider {
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border-color), transparent);
  margin: var(--spacing-8) 0;
}

/* News card glassmorphism */
.news-card {
  background: rgba(30, 41, 59, 0.6);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}

/* Smoother stat hover */
.stat {
  transition: transform var(--transition-fast);
  text-decoration: none;
}

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

/* Clickable stat link */
a.stat {
  cursor: pointer;
  position: relative;
}

a.stat:hover .stat-label {
  text-decoration: underline;
}

a.stat::after {
  content: '↗';
  position: absolute;
  top: 0;
  right: -8px;
  font-size: 0.75rem;
  color: var(--accent-primary);
  opacity: 0;
  transition: opacity var(--transition-fast);
}

a.stat:hover::after {
  opacity: 1;
}