:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f8f9fa;
  --bg-tertiary: #e9ecef;
  --text-primary: #1a1a1a;
  --text-secondary: #4a5568;
  --text-tertiary: #718096;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --border-color: #e2e8f0;
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --gradient-accent: linear-gradient(135deg, #3b82f6 0%, #2563eb 100%);
}

[data-theme="dark"] {
  --bg-primary: #0f1419;
  --bg-secondary: #1a1f2e;
  --bg-tertiary: #252d3d;
  --text-primary: #e2e8f0;
  --text-secondary: #cbd5e0;
  --text-tertiary: #a0aec0;
  --border-color: #2d3748;
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.3), 0 1px 2px 0 rgba(0, 0, 0, 0.2);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.3), 0 4px 6px -2px rgba(0, 0, 0, 0.2);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.3), 0 10px 10px -5px rgba(0, 0, 0, 0.2);
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: background-color 0.3s ease, color 0.3s ease;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 1rem;
  color: var(--text-primary);
}

h1 { font-size: 3rem; }
h2 { font-size: 2.25rem; }
h3 { font-size: 1.875rem; }
h4 { font-size: 1.5rem; }
h5 { font-size: 1.25rem; }
h6 { font-size: 1rem; }

p {
  margin-bottom: 1rem;
  color: var(--text-secondary);
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.2s ease;
}

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

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

.container-narrow {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 2rem;
}

/* Header */
header {
  position: sticky;
  top: 0;
  background-color: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
  padding: 1rem 0;
  z-index: 1000;
  backdrop-filter: blur(10px);
  background-color: rgba(255, 255, 255, 0.95);
}

[data-theme="dark"] header {
  background-color: rgba(15, 20, 25, 0.95);
}

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

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
}

.logo span {
  background: var(--gradient-accent);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

nav ul {
  display: flex;
  list-style: none;
  gap: 2rem;
  align-items: center;
}

nav a {
  color: var(--text-secondary);
  font-weight: 500;
  transition: color 0.2s ease;
}

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

.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1.25rem;
  padding: 0.5rem;
  color: var(--text-secondary);
  transition: color 0.2s ease;
}

.theme-toggle:hover {
  color: var(--accent);
}

.mobile-menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1.5rem;
  color: var(--text-primary);
}

/* Hero Section */
.hero {
  padding: 8rem 0 6rem;
  text-align: center;
}

.hero h1 {
  font-size: 3.5rem;
  margin-bottom: 1.5rem;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero .tagline {
  font-size: 1.5rem;
  color: var(--text-secondary);
  margin-bottom: 3rem;
  font-weight: 500;
}

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

.btn {
  padding: 0.875rem 2rem;
  border-radius: 0.5rem;
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  transition: all 0.2s ease;
  border: none;
  display: inline-block;
}

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

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

.btn-secondary {
  background: var(--bg-secondary);
  color: var(--text-primary);
  border: 2px solid var(--border-color);
}

.btn-secondary:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}

/* Sections */
section {
  padding: 5rem 0;
}

.section-header {
  text-align: center;
  margin-bottom: 4rem;
}

.section-header h2 {
  margin-bottom: 1rem;
}

.section-header p {
  font-size: 1.125rem;
  color: var(--text-tertiary);
}

/* Cards */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
}

.card {
  background: var(--bg-secondary);
  border-radius: 1rem;
  padding: 2rem;
  border: 1px solid var(--border-color);
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}

.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: var(--gradient-accent);
  transform: scaleX(0);
  transition: transform 0.3s ease;
}

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

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

.card-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

.card h3 {
  margin-bottom: 0.75rem;
  font-size: 1.25rem;
}

.card p {
  font-size: 0.95rem;
}

/* Featured Content */
.featured-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 2rem;
  margin-top: 3rem;
}

.featured-card {
  background: var(--bg-secondary);
  border-radius: 1rem;
  overflow: hidden;
  border: 1px solid var(--border-color);
  transition: all 0.3s ease;
}

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

.featured-image {
  width: 100%;
  height: 200px;
  background: var(--gradient-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 3rem;
}

.featured-content {
  padding: 2rem;
}

.featured-meta {
  color: var(--text-tertiary);
  font-size: 0.875rem;
  margin-bottom: 0.5rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-weight: 600;
}

.featured-content h3 {
  margin-bottom: 1rem;
  font-size: 1.5rem;
}

.read-more {
  color: var(--accent);
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin-top: 1rem;
}

.read-more:hover {
  gap: 0.75rem;
}

/* Blog & Case Studies List */
.post-list, .case-study-list {
  display: flex;
  flex-direction: column;
  gap: 2rem;
  max-width: 900px;
  margin: 0 auto;
}

.post-card, .case-study-card {
  background: var(--bg-secondary);
  border-radius: 1rem;
  padding: 2rem;
  border: 1px solid var(--border-color);
  transition: all 0.3s ease;
}

.post-card:hover, .case-study-card:hover {
  transform: translateX(8px);
  box-shadow: var(--shadow-lg);
}

.post-date, .case-study-meta {
  color: var(--text-tertiary);
  font-size: 0.875rem;
  margin-bottom: 0.5rem;
  font-weight: 600;
}

/* Article Content */
.article-header {
  text-align: center;
  margin-bottom: 3rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border-color);
}

.article-meta {
  color: var(--text-tertiary);
  font-size: 0.875rem;
  margin-bottom: 1rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.article-content {
  font-size: 1.125rem;
  line-height: 1.8;
}

.article-content h2 {
  margin-top: 3rem;
  margin-bottom: 1.5rem;
  font-size: 2rem;
}

.article-content h3 {
  margin-top: 2rem;
  margin-bottom: 1rem;
  font-size: 1.5rem;
}

.article-content p {
  margin-bottom: 1.5rem;
}

.article-content ul, .article-content ol {
  margin-bottom: 1.5rem;
  padding-left: 2rem;
  color: var(--text-secondary);
}

.article-content li {
  margin-bottom: 0.5rem;
}

.article-content code {
  background: var(--bg-tertiary);
  padding: 0.2rem 0.4rem;
  border-radius: 0.25rem;
  font-family: 'Monaco', 'Courier New', monospace;
  font-size: 0.9em;
  color: var(--accent);
}

.article-content pre {
  background: var(--bg-tertiary);
  padding: 1.5rem;
  border-radius: 0.5rem;
  overflow-x: auto;
  margin-bottom: 1.5rem;
  border: 1px solid var(--border-color);
}

.article-content pre code {
  background: none;
  padding: 0;
  color: var(--text-primary);
}

.callout {
  background: var(--bg-secondary);
  border-left: 4px solid var(--accent);
  padding: 1.5rem;
  margin: 2rem 0;
  border-radius: 0.5rem;
}

.callout-title {
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--accent);
}

.diagram {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  padding: 2rem;
  margin: 2rem 0;
  text-align: center;
}

.breadcrumb {
  padding: 2rem 0 1rem;
  color: var(--text-tertiary);
  font-size: 0.875rem;
}

.breadcrumb a {
  color: var(--text-tertiary);
}

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

/* Contact Page */
.contact-section {
  max-width: 600px;
  margin: 0 auto;
  text-align: center;
}

.contact-email {
  background: var(--bg-secondary);
  border: 2px solid var(--border-color);
  border-radius: 0.5rem;
  padding: 1rem 1.5rem;
  margin: 2rem 0;
  font-size: 1.25rem;
  color: var(--text-primary);
  font-weight: 600;
}

.social-links {
  display: flex;
  gap: 1.5rem;
  justify-content: center;
  margin-top: 2rem;
}

.social-link {
  font-size: 2rem;
  color: var(--text-secondary);
  transition: all 0.2s ease;
}

.social-link:hover {
  color: var(--accent);
  transform: translateY(-4px);
}

/* Footer */
footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 3rem 0 2rem;
  margin-top: 5rem;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 2rem;
}

.footer-links {
  display: flex;
  gap: 2rem;
}

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

.footer-social a {
  color: var(--text-tertiary);
  font-size: 1.25rem;
}

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

.copyright {
  width: 100%;
  text-align: center;
  margin-top: 2rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border-color);
  color: var(--text-tertiary);
  font-size: 0.875rem;
}

/* 404 Page */
.error-page {
  text-align: center;
  padding: 8rem 0;
}

.error-code {
  font-size: 8rem;
  font-weight: 700;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
  margin-bottom: 1rem;
}

/* Responsive */
@media (max-width: 768px) {
  .hero h1 {
    font-size: 2.5rem;
  }

  .hero .tagline {
    font-size: 1.25rem;
  }

  h1 { font-size: 2.5rem; }
  h2 { font-size: 2rem; }
  h3 { font-size: 1.5rem; }

  nav ul {
    display: none;
  }

  nav ul.mobile-open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    box-shadow: var(--shadow-lg);
  }

  .mobile-menu-toggle {
    display: block;
  }

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

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

  .footer-content {
    flex-direction: column;
    text-align: center;
  }

  section {
    padding: 3rem 0;
  }

  .container {
    padding: 0 1rem;
  }
}

/* Animations */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in-up {
  animation: fadeInUp 0.6s ease-out;
}

/* Utility Classes */
.text-center { text-align: center; }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }