:root {
  /* Earth-tone color palette */
  --terracotta: #22543d;
  --terracotta-light: #2a9d8f;
  --terracotta-dark: #1a4030;
  --sage: #7d8471;
  --sage-light: #a3ac96;
  --sand: #e8dfd0;
  --sand-light: #f5f1eb;
  --clay: #b8a99a;
  --charcoal: #2d2d2d;
  --charcoal-light: #4a4a4a;
  --cream: #fdfaf6;
  --white: #ffffff;

  /* Typography */
  --font-display: 'Playfair Display', Georgia, serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 2rem;
  --space-xl: 4rem;
  --space-2xl: 8rem;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 300ms ease;
  --transition-slow: 500ms ease;
}

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

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

body {
  font-family: var(--font-body);
  background-color: var(--cream);
  color: var(--charcoal);
  line-height: 1.7;
  overflow-x: hidden;
}

/* Typography */
h1,
h2,
h3,
h4 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.2;
  color: var(--charcoal);
}

h1 {
  font-size: clamp(2.5rem, 5vw, 4rem);
}

h2 {
  font-size: clamp(1.75rem, 3vw, 2.5rem);
  margin-bottom: var(--space-lg);
}

h3 {
  font-size: clamp(1.25rem, 2vw, 1.5rem);
}

p {
  max-width: 70ch;
  margin-bottom: var(--space-md);
}

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

a:hover {
  color: var(--terracotta-dark);
}

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

section {
  padding: var(--space-2xl) 0;
}

/* Navigation */
nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(253, 250, 246, 0.9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--sand);
  padding: var(--space-md) 0;
  transition: transform var(--transition-base);
}

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

.nav-logo {
  font-family: var(--font-display);
  font-size: 1.25rem;
  color: var(--charcoal);
  font-weight: 600;
}

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

.nav-links a {
  color: var(--charcoal-light);
  font-size: 0.9rem;
  font-weight: 500;
  transition: color var(--transition-fast);
}

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

/* Hero Section */
.hero {
  min-height: auto;
  padding: 120px 0 var(--space-2xl);
  background: linear-gradient(135deg, var(--cream) 0%, var(--sand-light) 100%);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 80%;
  height: 150%;
  background: radial-gradient(ellipse, var(--sand) 0%, transparent 70%);
  opacity: 0.5;
  pointer-events: none;
}

.hero-grid {
  display: grid;
  grid-template-columns: 35fr 65fr;
  gap: var(--space-xl);
  align-items: start;
  position: relative;
  z-index: 1;
}

@media (max-width: 900px) {
  .hero-grid {
    grid-template-columns: 1fr;
  }
}

.hero-left {
  position: relative;
}

.hero-right {
  position: relative;
}

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

.hero-badge {
  display: inline-block;
  background: var(--terracotta);
  color: var(--white);
  padding: var(--space-xs) var(--space-md);
  border-radius: 2rem;
  font-size: 0.85rem;
  font-weight: 500;
  margin-bottom: var(--space-lg);
  letter-spacing: 0.05em;
}

.hero h1 {
  margin-bottom: var(--space-lg);
  max-width: none;
  font-size: 2.5rem;
}

.hero h1 span {
  color: var(--terracotta);
}

/* Abstract Box */
.abstract-box {
  background: var(--white);
  border-radius: 0.75rem;
  padding: var(--space-md) var(--space-lg);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  border-left: 4px solid var(--terracotta);
}

.abstract-box h3 {
  font-family: var(--font-display);
  font-size: 1.1rem;
  color: var(--charcoal);
  margin-bottom: var(--space-sm);
}

.abstract-box p {
  font-size: 0.9rem;
  line-height: 1.6;
  color: var(--charcoal-light);
  margin-bottom: var(--space-sm);
}

.abstract-box p:last-child {
  margin-bottom: 0;
}

.abstract-box p strong {
  color: var(--charcoal);
}

/* Hero Figure (NFE plot) */
.hero-figure {
  margin-top: var(--space-md);
  background: var(--white);
  border-radius: 0.75rem;
  padding: var(--space-sm);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  text-align: center;
}

.hero-figure img {
  width: 100%;
  max-width: 100%;
  height: auto;
  border-radius: 0.5rem;
}

.hero-figure-caption {
  display: block;
  margin: var(--space-xs) auto 0;
  font-size: 0.8rem;
  color: var(--sage);
  font-style: italic;
  text-align: center;
  white-space: nowrap;
  max-width: none;
}

.hero-authors {
  font-size: 1.1rem;
  color: var(--charcoal-light);
  margin-bottom: var(--space-sm);
}

.hero-authors strong {
  color: var(--charcoal);
}

.hero-affiliations {
  font-size: 0.95rem;
  color: var(--sage);
  margin-bottom: var(--space-xl);
}

.hero-buttons {
  display: flex;
  gap: var(--space-md);
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: var(--space-sm) var(--space-md);
  border-radius: 0.375rem;
  font-weight: 500;
  font-size: 0.8rem;
  transition: all var(--transition-fast);
  cursor: pointer;
  border: none;
}

.btn svg {
  width: 16px;
  height: 16px;
}

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

.btn-primary:hover {
  background: var(--terracotta-dark);
  color: var(--white);
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(196, 112, 78, 0.3);
}

.btn-secondary {
  background: transparent;
  color: var(--charcoal);
  border: 2px solid var(--clay);
}

.btn-secondary:hover {
  border-color: var(--terracotta);
  color: var(--terracotta);
}

/* Abstract Section */
.abstract {
  background: var(--white);
  border-top: 1px solid var(--sand);
  border-bottom: 1px solid var(--sand);
}

.abstract-content {
  max-width: 800px;
  margin: 0 auto;
  text-align: center;
}

.abstract-content p {
  font-size: 1.15rem;
  line-height: 1.9;
  color: var(--charcoal-light);
  max-width: none;
}

.abstract-content p strong {
  color: var(--charcoal);
}

/* Key Idea Section */
.key-idea {
  background: var(--sand-light);
}

.key-idea-content {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-xl);
  align-items: center;
}

.diagram-container {
  background: var(--white);
  padding: var(--space-lg);
  border-radius: 1rem;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
}

.diagram-container.centered {
  max-width: 900px;
  margin: 0 auto;
}

.diagram-container img {
  width: 100%;
  height: auto;
  display: block;
}

.diagram-caption {
  margin-top: var(--space-md);
  margin-bottom: 0;
  font-size: 0.9rem;
  color: var(--sage);
  text-align: center;
  font-style: italic;
  max-width: none;
}

/* Mathematical Definitions */
.math-definitions {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-lg);
  margin-top: var(--space-xl);
  margin-bottom: var(--space-xl);
  max-width: 900px;
  margin-left: auto;
  margin-right: auto;
}

@media (max-width: 768px) {
  .math-definitions {
    grid-template-columns: 1fr;
  }
}

.definition-card {
  background: var(--white);
  border-radius: 0.75rem;
  overflow: hidden;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
  border: 1px solid var(--terracotta);
}

.definition-header {
  background: var(--terracotta);
  color: var(--white);
  padding: var(--space-sm) var(--space-md);
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.definition-body {
  padding: var(--space-md);
}

.definition-body p {
  font-size: 0.9rem;
  color: var(--charcoal-light);
  margin-bottom: var(--space-sm);
  line-height: 1.6;
}

.definition-body p:last-child {
  margin-bottom: 0;
}

.definition-note {
  font-size: 0.85rem !important;
  color: var(--sage) !important;
  font-style: italic;
  border-top: 1px solid var(--sand);
  padding-top: var(--space-sm);
  margin-top: var(--space-sm) !important;
}

.math-display {
  text-align: center;
  padding: var(--space-md) 0;
  background: var(--sand-light);
  border-radius: 0.5rem;
  margin: var(--space-sm) 0;
}

.math-connection {
  max-width: 900px;
  margin: var(--space-xl) auto 0;
  padding: var(--space-lg);
  background: var(--white);
  border-radius: 0.75rem;
  border: 1px solid var(--terracotta);
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--charcoal-light);
  text-align: center;
}

.math-connection strong {
  color: var(--terracotta);
}

.math-connection em {
  color: var(--charcoal);
  font-style: italic;
}

/* Button with note */
.btn-with-note {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-xs);
}

.btn-note {
  font-size: 0.8rem;
  color: var(--sage);
  font-style: italic;
}

.btn-disabled {
  opacity: 0.6;
  cursor: not-allowed;
  pointer-events: none;
}

/* Contributions Section */
.contributions {
  background: var(--cream);
}

.contributions-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-lg);
  margin-top: var(--space-xl);
}

.contribution-card {
  background: var(--white);
  padding: var(--space-xl);
  border-radius: 1rem;
  border: 1px solid var(--sand);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.contribution-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: var(--terracotta);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--transition-base);
}

.contribution-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.08);
}

.contribution-card:hover::before {
  transform: scaleX(1);
}

.contribution-number {
  font-family: var(--font-display);
  font-size: 3rem;
  color: var(--sand);
  font-weight: 700;
  line-height: 1;
  margin-bottom: var(--space-md);
}

.contribution-card h3 {
  margin-bottom: var(--space-md);
  color: var(--charcoal);
}

.contribution-card p {
  color: var(--charcoal-light);
  font-size: 0.95rem;
}

/* Results Section */
.results {
  background: var(--white);
}

.results-header {
  text-align: center;
  max-width: 700px;
  margin: 0 auto var(--space-xl);
}

.results-header p {
  color: var(--charcoal-light);
  max-width: none;
}

/* Image Grid */
.image-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-md);
  margin-bottom: var(--space-xl);
}

.image-card {
  background: var(--sand-light);
  border-radius: 0.75rem;
  overflow: hidden;
  transition: transform var(--transition-base);
}

.image-card:hover {
  transform: scale(1.02);
}

.image-card img {
  width: 100%;
  height: auto;
  display: block;
}

.image-card-label {
  padding: var(--space-sm) var(--space-md);
  font-size: 0.85rem;
  color: var(--charcoal-light);
  text-align: center;
  background: var(--white);
}

/* Comparison Grid */
.comparison-section {
  margin-top: var(--space-2xl);
}

.comparison-section h3 {
  text-align: center;
  margin-bottom: var(--space-lg);
}

.comparison-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-lg);
}

.comparison-pair {
  background: var(--sand-light);
  border-radius: 1rem;
  padding: var(--space-lg);
}

.comparison-pair h4 {
  text-align: center;
  margin-bottom: var(--space-md);
  color: var(--sage);
  font-size: 0.9rem;
  font-family: var(--font-body);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.comparison-images {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
}

.comparison-item {
  text-align: center;
}

.comparison-item img {
  width: 100%;
  border-radius: 0.5rem;
  margin-bottom: var(--space-sm);
}

.comparison-item span {
  font-size: 0.8rem;
  color: var(--charcoal-light);
}

/* Stats Section */
.stats {
  background: var(--charcoal);
  color: var(--white);
}

.stats h2 {
  color: var(--white);
  text-align: center;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-xl);
  margin-top: var(--space-xl);
}

.stat-item {
  text-align: center;
}

.stat-value {
  font-family: var(--font-display);
  font-size: 3.5rem;
  font-weight: 700;
  color: var(--terracotta-light);
  line-height: 1;
  margin-bottom: var(--space-sm);
}

.stat-label {
  color: var(--clay);
  font-size: 0.95rem;
}

/* BibTeX Section */
.bibtex {
  background: var(--sand-light);
}

.bibtex-container {
  max-width: 800px;
  margin: 0 auto;
}

.bibtex-box {
  background: var(--charcoal);
  border-radius: 0.75rem;
  padding: var(--space-lg);
  position: relative;
  overflow: hidden;
}

.bibtex-box pre {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--sand);
  white-space: pre-wrap;
  word-break: break-all;
  line-height: 1.6;
}

.copy-btn {
  position: absolute;
  top: var(--space-md);
  right: var(--space-md);
  background: var(--terracotta);
  color: var(--white);
  border: none;
  padding: var(--space-sm) var(--space-md);
  border-radius: 0.375rem;
  font-size: 0.8rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.copy-btn:hover {
  background: var(--terracotta-light);
}

.copy-btn.copied {
  background: var(--sage);
}

/* Footer */
footer {
  background: var(--cream);
  border-top: 1px solid var(--sand);
  padding: var(--space-xl) 0;
  text-align: center;
}

footer p {
  color: var(--sage);
  font-size: 0.9rem;
  max-width: none;
}

footer a {
  color: var(--terracotta);
}

/* Animations */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }

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

.animate-in {
  animation: fadeInUp 0.6s ease forwards;
}

.animate-delay-1 {
  animation-delay: 0.1s;
}

.animate-delay-2 {
  animation-delay: 0.2s;
}

.animate-delay-3 {
  animation-delay: 0.3s;
}

.animate-delay-4 {
  animation-delay: 0.4s;
}

/* Responsive */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .hero-buttons {
    flex-direction: column;
  }

  .btn {
    justify-content: center;
  }

  section {
    padding: var(--space-xl) 0;
  }

  .comparison-images {
    grid-template-columns: 1fr;
  }
}

@media (min-width: 1024px) {
  .key-idea-content {
    grid-template-columns: 1fr;
  }
}

/* Utility Classes */
.text-center {
  text-align: center;
}

.text-muted {
  color: var(--charcoal-light);
}

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

.mt-xl {
  margin-top: var(--space-xl);
}

/* Motivation + Contributions Section */
.motivation-contributions {
  background: var(--white);
  border-top: 1px solid var(--sand);
  border-bottom: 1px solid var(--sand);
}

/* Motivation + Contributions Grid */
.motivation-contributions-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-xl);
  align-items: start;
}

@media (max-width: 900px) {
  .motivation-contributions-grid {
    grid-template-columns: 1fr;
  }
}

/* Motivation Section */
.motivation-section {
  margin-bottom: 0;
}

.motivation-section h2 {
  margin-bottom: var(--space-lg);
}

.motivation-content {
  max-width: none;
  margin: 0;
  text-align: left;
}

.motivation-content p {
  font-size: 1rem;
  line-height: 1.7;
  color: var(--charcoal-light);
  max-width: none;
}

.motivation-content p strong {
  color: var(--charcoal);
}

/* Contributions Box Standalone */
.contributions-box-standalone {
  background: var(--white);
  border: 2px solid var(--terracotta);
  border-radius: 1rem;
  padding: var(--space-xl);
  max-width: 900px;
  margin: 0 auto;
}

.contributions-box-standalone h3 {
  color: var(--terracotta);
  margin-bottom: var(--space-lg);
  font-size: 1.5rem;
}

/* Contributions Box */
.contributions-box {
  background: var(--white);
  border: 2px solid var(--terracotta);
  border-radius: 0.75rem;
  padding: var(--space-md) var(--space-lg);
}

.contributions-box h3 {
  color: var(--terracotta);
  margin-bottom: var(--space-sm);
  font-size: 1.25rem;
}

.contributions-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.contributions-list li {
  position: relative;
  padding-left: var(--space-lg);
  margin-bottom: var(--space-sm);
  line-height: 1.5;
  color: var(--charcoal-light);
}

.contributions-list li:last-child {
  margin-bottom: 0;
}

.contributions-list li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.4rem;
  width: 8px;
  height: 8px;
  background: var(--terracotta);
  border-radius: 50%;
}

.contributions-list li strong {
  color: var(--charcoal);
}

.contributions-list li em {
  color: var(--terracotta-dark);
  font-style: normal;
  font-weight: 500;
}

/* Carousel */
.carousel-section {
  margin-top: var(--space-xl);
}

.carousel {
  position: relative;
  max-width: 1000px;
  margin: 0 auto;
}

.carousel-track {
  overflow: hidden;
  border-radius: 0.75rem;
  background: var(--sand-light);
  position: relative;
  height: 420px;
}

.carousel-slides-wrapper {
  display: flex;
  transition: transform 0.5s ease;
}

.carousel-slide {
  min-width: 100%;
  padding: var(--space-sm) var(--space-md);
  box-sizing: border-box;
  height: 420px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  overflow: hidden;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateX(30px);
  }

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

.slide-title {
  text-align: center;
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--charcoal);
  margin-bottom: var(--space-sm);
}

.slide-caption {
  text-align: center;
  font-size: 0.85rem;
  color: var(--sage);
  margin-top: var(--space-sm);
  font-style: italic;
  max-width: none;
}

/* Carousel Buttons */
.carousel-btn {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 48px;
  height: 48px;
  border: none;
  border-radius: 50%;
  background: var(--white);
  color: var(--charcoal);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  transition: all var(--transition-fast);
  z-index: 10;
}

.carousel-btn:hover {
  background: var(--terracotta);
  color: var(--white);
}

.carousel-prev {
  left: -24px;
}

.carousel-next {
  right: -24px;
}

/* Carousel Dots */
.carousel-dots {
  display: flex;
  justify-content: center;
  gap: var(--space-sm);
  margin-top: var(--space-lg);
}

.carousel-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--clay);
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.carousel-dot.active {
  background: var(--terracotta);
  transform: scale(1.2);
}

/* Carousel Image Grid (small) */
.image-grid-small {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-sm);
  max-width: 500px;
  margin: 0 auto;
}

.image-card-small {
  text-align: center;
}

.image-card-small img {
  width: 100%;
  max-width: 140px;
  border-radius: 0.375rem;
  margin-bottom: var(--space-xs);
}

.image-card-small span {
  font-size: 0.75rem;
  color: var(--charcoal-light);
}

/* Comparison Row */
.comparison-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-lg);
  flex-wrap: wrap;
}

.comparison-item-large {
  text-align: center;
  flex: 0 0 auto;
}

.comparison-item-large img {
  width: 200px;
  height: 200px;
  object-fit: cover;
  border-radius: 0.5rem;
  margin-bottom: var(--space-xs);
}

.comparison-item-large span {
  display: block;
  font-size: 0.85rem;
  color: var(--charcoal-light);
}

.arrow-icon {
  font-size: 2rem;
  color: var(--terracotta);
}

/* Figure Container */
.figure-container {
  text-align: center;
}

.figure-container img {
  max-width: 100%;
  max-height: 320px;
  border-radius: 0.5rem;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.figure-container-row {
  display: flex;
  justify-content: center;
  gap: var(--space-lg);
  flex-wrap: wrap;
}

.figure-container-row img {
  max-width: 45%;
  max-height: 320px;
  border-radius: 0.5rem;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

/* Fine-tuning grid */
.finetune-grid {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  align-items: center;
}

.finetune-grid img {
  max-width: 100%;
  max-height: 140px;
  border-radius: 0.5rem;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

/* Steering 2x2 grid */
.steering-grid-2x2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-sm);
  max-width: 700px;
  margin: 0 auto;
}

.steering-grid-2x2 img {
  width: 100%;
  max-height: 160px;
  object-fit: contain;
  border-radius: 0.375rem;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
}

/* Responsive carousel */
@media (max-width: 768px) {
  .carousel-btn {
    width: 36px;
    height: 36px;
  }

  .carousel-prev {
    left: 8px;
  }

  .carousel-next {
    right: 8px;
  }

  .image-grid-small {
    grid-template-columns: repeat(2, 1fr);
  }

  .comparison-item-large img {
    width: 150px;
    height: 150px;
  }

  .figure-container-row img {
    max-width: 100%;
  }
}