/* Design System & Custom Properties */
:root {
  /* Common Variables */
  --font-body: 'Inter', sans-serif;
  --font-heading: 'Outfit', sans-serif;
  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
  --transition-slow: 0.5s ease;
  --border-radius-sm: 8px;
  --border-radius-md: 16px;
  --border-radius-lg: 24px;
  --container-max-width: 1100px;

  /* Theme: Dark (Default) */
  --bg-primary: hsl(222, 25%, 10%);
  --bg-secondary: hsl(222, 25%, 14%);
  --bg-glass: rgba(15, 23, 42, 0.65);
  --bg-card: rgba(30, 41, 59, 0.45);
  --bg-card-hover: rgba(30, 41, 59, 0.7);
  
  --text-primary: hsl(210, 40%, 98%);
  --text-secondary: hsl(215, 20%, 75%);
  --text-muted: hsl(215, 15%, 55%);
  
  --accent-primary: hsl(190, 100%, 45%); /* Neon Cyan */
  --accent-secondary: hsl(265, 100%, 70%); /* Bright Purple */
  --accent-glow: rgba(6, 182, 212, 0.15);
  
  --border-color: rgba(255, 255, 255, 0.08);
  --border-hover: rgba(6, 182, 212, 0.3);
  --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.5);
  
  --gradient-text: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  --gradient-glow: radial-gradient(circle, rgba(6, 182, 212, 0.15) 0%, rgba(139, 92, 246, 0.05) 50%, transparent 100%);
}

/* Light Theme Variables */
[data-theme="light"] {
  --bg-primary: hsl(210, 40%, 98%);
  --bg-secondary: hsl(210, 30%, 95%);
  --bg-glass: rgba(255, 255, 255, 0.75);
  --bg-card: rgba(255, 255, 255, 0.8);
  --bg-card-hover: rgba(255, 255, 255, 0.95);
  
  --text-primary: hsl(222, 47%, 11%);
  --text-secondary: hsl(217, 19%, 35%);
  --text-muted: hsl(215, 16%, 52%);
  
  --accent-primary: hsl(190, 95%, 38%);
  --accent-secondary: hsl(265, 85%, 50%);
  --accent-glow: rgba(6, 182, 212, 0.08);
  
  --border-color: rgba(0, 0, 0, 0.06);
  --border-hover: rgba(6, 182, 212, 0.4);
  --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 10px 15px -3px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  
  --gradient-glow: radial-gradient(circle, rgba(6, 182, 212, 0.08) 0%, rgba(139, 92, 246, 0.03) 60%, transparent 100%);
}

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

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

body {
  font-family: var(--font-body);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  transition: background-color var(--transition-slow), color var(--transition-slow);
}

/* Ambient glow backgrounds */
.ambient-glow {
  position: fixed;
  top: -10%;
  right: -10%;
  width: 60vw;
  height: 60vw;
  background: var(--gradient-glow);
  z-index: -1;
  pointer-events: none;
  border-radius: 50%;
  filter: blur(80px);
}

.ambient-glow-2 {
  position: fixed;
  bottom: -10%;
  left: -10%;
  width: 50vw;
  height: 50vw;
  background: var(--gradient-glow);
  z-index: -1;
  pointer-events: none;
  border-radius: 50%;
  filter: blur(80px);
  transform: rotate(180deg);
}

/* Typography */
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: -0.02em;
}

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

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

/* Layout */
.container {
  width: 100%;
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header & Navigation */
header.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  transition: background-color var(--transition-slow), border-color var(--transition-slow);
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 70px;
}

.logo {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 800;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.03em;
}

.nav-right {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.nav-links {
  display: flex;
  gap: 1.5rem;
  list-style: none;
}

.nav-links a {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-secondary);
}

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

/* Theme Toggle Button */
.theme-toggle {
  background: none;
  border: 1px solid var(--border-color);
  cursor: pointer;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-primary);
  transition: background-color var(--transition-fast), border-color var(--transition-fast), transform var(--transition-fast);
}

.theme-toggle:hover {
  background-color: var(--bg-secondary);
  border-color: var(--accent-primary);
  transform: scale(1.05);
}

.theme-toggle svg {
  width: 20px;
  height: 20px;
  fill: currentColor;
}

[data-theme="light"] .theme-toggle .sun-icon {
  display: none;
}
[data-theme="dark"] .theme-toggle .moon-icon {
  display: none;
}

/* Hero Section */
/* Hero Section */
.hero {
  padding: 6rem 0 4rem;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 2rem;
  max-width: 800px;
}

@media (max-width: 768px) {
  .hero {
    padding: 4rem 0 3rem;
    align-items: flex-start;
  }
}

.hero-content {
  animation: fadeInUp 0.8s cubic-bezier(0.16, 1, 0.3, 1);
  width: 100%;
}

.hero-subtitle {
  font-size: 1.1rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.5rem;
}

.hero-title {
  font-size: 3.5rem;
  margin-bottom: 1.2rem;
  color: var(--text-primary);
}

@media (max-width: 576px) {
  .hero-title {
    font-size: 2.5rem;
  }
}

.hero-bio {
  font-size: 1.15rem;
  color: var(--text-secondary);
  margin-bottom: 2rem;
  width: 100%;
}

.hero-highlights {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
  margin-bottom: 2.5rem;
  width: 100%;
}

.highlight-item {
  display: flex;
  align-items: flex-start;
  gap: 0.8rem;
  font-size: 1.05rem;
  color: var(--text-secondary);
}

.highlight-icon {
  font-size: 1.25rem;
  line-height: 1.4;
}

.hero-cta-text {
  font-size: 1.15rem;
  color: var(--text-secondary);
  margin-bottom: 3.5rem;
  width: 100%;
  line-height: 1.6;
}

.btn-social.primary {
  background: var(--gradient-text);
  color: hsl(222, 25%, 10%);
  border: none;
  font-weight: 700;
}

[data-theme="light"] .btn-social.primary {
  color: white;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
}

.btn-social.primary:hover {
  box-shadow: 0 4px 15px rgba(6, 182, 212, 0.4);
  color: hsl(222, 25%, 10%);
}

[data-theme="light"] .btn-social.primary:hover {
  color: white;
}

/* Quick social link bar */
.social-bar {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

@media (max-width: 768px) {
  .social-bar {
    justify-content: center;
  }
}

.btn-social {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 1.2rem;
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  border-radius: var(--border-radius-sm);
  font-size: 0.9rem;
  font-weight: 500;
  transition: background-color var(--transition-fast), border-color var(--transition-fast), transform var(--transition-fast);
}

.btn-social:hover {
  background-color: var(--bg-card-hover);
  border-color: var(--accent-primary);
  transform: translateY(-2px);
  color: var(--accent-primary);
}

.btn-social svg {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

/* Section Header */
.section-title-wrap {
  margin-top: 5rem;
  margin-bottom: 2rem;
  display: flex;
  align-items: center;
  gap: 1rem;
}

.section-title {
  font-size: 2rem;
  color: var(--text-primary);
}

.section-line {
  flex-grow: 1;
  height: 1px;
  background: linear-gradient(90deg, var(--border-color), transparent);
}

/* Publications List */
.publications-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
}

.publication-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
  position: relative;
  overflow: hidden;
  transition: background-color var(--transition-normal), border-color var(--transition-normal), transform var(--transition-normal), box-shadow var(--transition-normal);
}

.publication-card:hover {
  background-color: var(--bg-card-hover);
  border-color: var(--border-hover);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

.publication-meta {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.8rem;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
}

.pub-number {
  background-color: var(--bg-secondary);
  color: var(--accent-primary);
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
}

.pub-venue {
  font-style: italic;
  color: var(--text-secondary);
}

.publication-title {
  font-size: 1.2rem;
  color: var(--text-primary);
  font-weight: 600;
  line-height: 1.4;
}

.publication-card a.pub-title-link:hover {
  color: var(--accent-primary);
}

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

.pub-actions {
  display: flex;
  gap: 0.8rem;
  margin-top: 0.5rem;
}

.btn-pub-action {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.4rem 0.8rem;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-sm);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-secondary);
  transition: background-color var(--transition-fast), border-color var(--transition-fast), color var(--transition-fast);
}

.btn-pub-action:hover {
  background-color: var(--bg-primary);
  border-color: var(--accent-primary);
  color: var(--accent-primary);
}

.btn-pub-action svg {
  width: 14px;
  height: 14px;
  fill: currentColor;
}

/* Repositories Grid */
.repos-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 1.5rem;
}

@media (max-width: 576px) {
  .repos-grid {
    grid-template-columns: 1fr;
  }
}

.repo-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: 1.8rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 1.2rem;
  transition: background-color var(--transition-normal), border-color var(--transition-normal), transform var(--transition-normal), box-shadow var(--transition-normal);
}

.repo-card:hover {
  background-color: var(--bg-card-hover);
  border-color: var(--border-hover);
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.repo-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}

.repo-title {
  font-size: 1.3rem;
  color: var(--text-primary);
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.repo-icon {
  color: var(--accent-primary);
}

.repo-icon svg {
  width: 24px;
  height: 24px;
  fill: currentColor;
}

.repo-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  flex-grow: 1;
}

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

.repo-tag {
  background-color: var(--bg-secondary);
  color: var(--text-secondary);
  font-size: 0.75rem;
  font-weight: 500;
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
  border: 1px solid var(--border-color);
}

.repo-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-top: 1px solid var(--border-color);
  padding-top: 1rem;
}

.repo-link {
  font-size: 0.9rem;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
}

.repo-link svg {
  width: 16px;
  height: 16px;
  fill: currentColor;
  transition: transform var(--transition-fast);
}

.repo-link:hover svg {
  transform: translateX(3px);
}

/* Footer */
footer.site-footer {
  margin-top: 8rem;
  padding: 4rem 0 3rem;
  border-top: 1px solid var(--border-color);
  background-color: var(--bg-secondary);
  transition: background-color var(--transition-slow), border-color var(--transition-slow);
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1.5rem;
}

@media (max-width: 576px) {
  .footer-content {
    flex-direction: column;
    text-align: center;
  }
}

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

.footer-socials {
  display: flex;
  gap: 1rem;
}

.footer-social-link {
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

.footer-social-link:hover {
  color: var(--accent-primary);
}

.footer-social-link svg {
  width: 20px;
  height: 20px;
  fill: currentColor;
}

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

@keyframes float {
  0% {
    transform: translateY(0px);
  }
  50% {
    transform: translateY(-8px);
  }
  100% {
    transform: translateY(0px);
  }
}

@keyframes rotate {
  100% {
    transform: rotate(360deg);
  }
}

/* Fade in class for list animations */
.fade-in-section {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
  visibility: hidden;
}

.fade-in-section.is-visible {
  opacity: 1;
  transform: none;
  visibility: visible;
}