/* ============================================
   VLB2.de - Modern Design System
   ============================================ */

:root {
  /* Colors */
  --primary: #2563eb;
  --primary-dark: #1e40af;
  --secondary: #8b5cf6;
  --accent: #06b6d4;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  
  /* Neutrals */
  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-400: #9ca3af;
  --gray-500: #6b7280;
  --gray-600: #4b5563;
  --gray-700: #374151;
  --gray-800: #1f2937;
  --gray-900: #111827;
  
  /* Gradients */
  --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --gradient-hero: linear-gradient(135deg, #1e3a8a 0%, #3b82f6 50%, #8b5cf6 100%);
  --gradient-card: linear-gradient(135deg, rgba(37, 99, 235, 0.1) 0%, rgba(139, 92, 246, 0.1) 100%);
  
  /* Typography */
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, monospace;
  
  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-2xl: 4rem;
  --spacing-3xl: 6rem;
  
  /* Borders */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --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);
  --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
  
  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-base: 200ms ease-in-out;
  --transition-slow: 300ms ease-in-out;
}

/* ============================================
   Reset & Base Styles
   ============================================ */

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

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

body {
  font-family: var(--font-sans);
  line-height: 1.7;
  color: var(--gray-800);
  background: var(--gray-50);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   Typography
   ============================================ */

h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: var(--spacing-md);
  color: var(--gray-900);
}

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: 1.125rem; }

p {
  margin-bottom: var(--spacing-md);
  color: var(--gray-700);
}

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

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

code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--gray-100);
  padding: 0.125rem 0.375rem;
  border-radius: var(--radius-sm);
  color: var(--danger);
}

pre {
  background: var(--gray-900);
  color: var(--gray-100);
  padding: var(--spacing-md);
  border-radius: var(--radius-lg);
  overflow-x: auto;
  margin-bottom: var(--spacing-md);
  position: relative;
}

pre code {
  background: none;
  color: inherit;
  padding: 0;
  font-size: 0.875rem;
  line-height: 1.6;
}

blockquote {
  border-left: 4px solid var(--primary);
  padding-left: var(--spacing-md);
  margin: var(--spacing-lg) 0;
  font-style: italic;
  color: var(--gray-600);
}

/* ============================================
   Header & Navigation
   ============================================ */

header {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 1000;
  border-bottom: 1px solid var(--gray-200);
}

nav {
  max-width: 1280px;
  margin: 0 auto;
  padding: var(--spacing-md) var(--spacing-lg);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.5rem;
  font-weight: 800;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.02em;
}

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

.nav-links a {
  color: var(--gray-700);
  font-weight: 500;
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--primary);
  background: rgba(37, 99, 235, 0.1);
}

/* Mobile Menu */
.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--gray-700);
}

@media (max-width: 768px) {
  .mobile-menu-btn {
    display: block;
  }
  
  .nav-links {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: white;
    flex-direction: column;
    padding: var(--spacing-md);
    box-shadow: var(--shadow-lg);
    display: none;
    gap: 0;
  }
  
  .nav-links.active {
    display: flex;
  }
  
  .nav-links li {
    width: 100%;
  }
  
  .nav-links a {
    display: block;
    padding: var(--spacing-sm);
  }
}

/* ============================================
   Hero Section
   ============================================ */

.hero {
  background: var(--gradient-hero);
  color: white;
  padding: var(--spacing-3xl) var(--spacing-lg);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: url('data:image/svg+xml,<svg width="100" height="100" xmlns="http://www.w3.org/2000/svg"><defs><pattern id="grid" width="100" height="100" patternUnits="userSpaceOnUse"><path d="M 100 0 L 0 0 0 100" fill="none" stroke="rgba(255,255,255,0.05)" stroke-width="1"/></pattern></defs><rect width="100%" height="100%" fill="url(%23grid)"/></svg>');
  opacity: 0.3;
}

.hero-content {
  max-width: 800px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
  animation: fadeInUp 0.8s ease-out;
}

.hero h1 {
  font-size: 4rem;
  margin-bottom: var(--spacing-md);
  color: white;
  text-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.hero .subtitle {
  font-size: 1.5rem;
  margin-bottom: var(--spacing-sm);
  font-weight: 600;
  opacity: 0.95;
}

.hero p {
  font-size: 1.125rem;
  margin-bottom: var(--spacing-xl);
  opacity: 0.9;
  color: white;
}

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

/* ============================================
   Buttons
   ============================================ */

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: var(--radius-lg);
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  transition: all var(--transition-base);
  border: 2px solid transparent;
  text-decoration: none;
}

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

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

.btn-secondary {
  background: rgba(255, 255, 255, 0.1);
  color: white;
  border-color: rgba(255, 255, 255, 0.3);
  backdrop-filter: blur(10px);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.2);
  border-color: rgba(255, 255, 255, 0.5);
}

/* ============================================
   Container & Grid
   ============================================ */

.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: var(--spacing-2xl) var(--spacing-lg);
}

.section {
  padding: var(--spacing-3xl) 0;
}

.section-title {
  text-align: center;
  margin-bottom: var(--spacing-xl);
}

.section-title h2 {
  font-size: 2.5rem;
  margin-bottom: var(--spacing-sm);
}

.section-title p {
  font-size: 1.125rem;
  color: var(--gray-600);
  max-width: 600px;
  margin: 0 auto;
}

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

.grid-2 { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.grid-4 { grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); }

/* ============================================
   Cards
   ============================================ */

.card {
  background: white;
  border-radius: var(--radius-xl);
  padding: var(--spacing-lg);
  box-shadow: var(--shadow-md);
  transition: all var(--transition-base);
  border: 1px solid var(--gray-200);
  height: 100%;
  display: flex;
  flex-direction: column;
}

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

.card-icon {
  font-size: 2.5rem;
  margin-bottom: var(--spacing-md);
  display: inline-block;
}

.card h3 {
  font-size: 1.25rem;
  margin-bottom: var(--spacing-sm);
  color: var(--gray-900);
}

.card p {
  color: var(--gray-600);
  flex-grow: 1;
}

.card-link {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  color: var(--primary);
  font-weight: 600;
  margin-top: var(--spacing-md);
  transition: gap var(--transition-fast);
}

.card-link:hover {
  gap: var(--spacing-sm);
}

/* Feature Card */
.feature-card {
  text-align: center;
}

.feature-card .card-icon {
  background: var(--gradient-card);
  width: 80px;
  height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-xl);
  margin: 0 auto var(--spacing-md);
}

/* Blog Card */
.blog-card {
  overflow: hidden;
}

.blog-card-image {
  width: 100%;
  height: 200px;
  object-fit: cover;
  margin: calc(var(--spacing-lg) * -1);
  margin-bottom: var(--spacing-md);
  border-radius: var(--radius-xl) var(--radius-xl) 0 0;
}

.blog-card-meta {
  display: flex;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-sm);
  color: var(--gray-500);
  font-size: 0.875rem;
}

.blog-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-xs);
  margin-top: var(--spacing-md);
}

.tag {
  background: var(--gray-100);
  color: var(--gray-700);
  padding: 0.25rem 0.75rem;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 500;
  transition: all var(--transition-fast);
}

.tag:hover {
  background: var(--primary);
  color: white;
}

/* ============================================
   Blog Post
   ============================================ */

.post-header {
  text-align: center;
  margin-bottom: var(--spacing-xl);
  padding-bottom: var(--spacing-xl);
  border-bottom: 2px solid var(--gray-200);
}

.post-header h1 {
  font-size: 3rem;
  margin-bottom: var(--spacing-md);
}

.post-meta {
  display: flex;
  justify-content: center;
  gap: var(--spacing-lg);
  color: var(--gray-500);
  font-size: 0.9375rem;
}

.post-image {
  width: 100%;
  max-height: 500px;
  object-fit: cover;
  border-radius: var(--radius-2xl);
  margin-bottom: var(--spacing-xl);
  box-shadow: var(--shadow-lg);
}

.post-content {
  max-width: 800px;
  margin: 0 auto;
  font-size: 1.125rem;
  line-height: 1.8;
}

.post-content h2 {
  margin-top: var(--spacing-2xl);
  margin-bottom: var(--spacing-md);
  padding-top: var(--spacing-md);
  border-top: 2px solid var(--gray-200);
}

.post-content h3 {
  margin-top: var(--spacing-xl);
}

.post-content img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-lg);
  margin: var(--spacing-lg) 0;
}

.post-content ul,
.post-content ol {
  margin-bottom: var(--spacing-md);
  padding-left: var(--spacing-lg);
}

.post-content li {
  margin-bottom: var(--spacing-sm);
}

/* Table of Contents */
.toc {
  background: var(--gray-50);
  border: 2px solid var(--gray-200);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-xl);
}

.toc h2 {
  font-size: 1.25rem;
  margin-bottom: var(--spacing-sm);
  border: none;
  padding: 0;
  margin-top: 0;
}

.toc ul {
  list-style: none;
  padding-left: var(--spacing-md);
}

.toc li {
  margin-bottom: var(--spacing-xs);
}

.toc a {
  color: var(--gray-700);
  transition: color var(--transition-fast);
}

.toc a:hover {
  color: var(--primary);
}

/* Reading Progress Bar */
.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: var(--gray-200);
  z-index: 9999;
}

.reading-progress-bar {
  height: 100%;
  background: var(--gradient-primary);
  width: 0%;
  transition: width 100ms ease-out;
}

/* ============================================
   Footer
   ============================================ */

footer {
  background: var(--gray-900);
  color: var(--gray-300);
  padding: var(--spacing-2xl) var(--spacing-lg);
  margin-top: var(--spacing-3xl);
}

.footer-content {
  max-width: 1280px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-xl);
}

.footer-section h3 {
  color: white;
  margin-bottom: var(--spacing-md);
  font-size: 1.125rem;
}

.footer-section p,
.footer-section a {
  color: var(--gray-400);
  font-size: 0.9375rem;
}

.footer-section a:hover {
  color: white;
}

.footer-bottom {
  max-width: 1280px;
  margin: var(--spacing-xl) auto 0;
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--gray-700);
  text-align: center;
  color: var(--gray-500);
  font-size: 0.875rem;
}

/* ============================================
   Utilities
   ============================================ */

.text-center { text-align: center; }
.text-muted { color: var(--gray-600); }
.mt-lg { margin-top: var(--spacing-lg); }
.mb-lg { margin-bottom: var(--spacing-lg); }

/* ============================================
   Animations
   ============================================ */

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

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

/* ============================================
   Responsive
   ============================================ */

@media (max-width: 1024px) {
  h1 { font-size: 2.5rem; }
  h2 { font-size: 2rem; }
  .hero h1 { font-size: 3rem; }
}

@media (max-width: 768px) {
  :root {
    font-size: 15px;
  }
  
  h1 { font-size: 2rem; }
  h2 { font-size: 1.75rem; }
  .hero h1 { font-size: 2.25rem; }
  
  .container {
    padding: var(--spacing-xl) var(--spacing-md);
  }
  
  .section {
    padding: var(--spacing-2xl) 0;
  }
  
  .hero {
    padding: var(--spacing-2xl) var(--spacing-md);
  }
  
  .hero-buttons {
    flex-direction: column;
  }
  
  .btn {
    width: 100%;
    justify-content: center;
  }
  
  .post-header h1 {
    font-size: 2rem;
  }
  
  .post-meta {
    flex-direction: column;
    gap: var(--spacing-xs);
  }
}

@media (max-width: 480px) {
  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
  }
}

/* ============================================
   Print Styles
   ============================================ */

@media print {
  header,
  footer,
  .hero-buttons,
  .reading-progress {
    display: none;
  }
  
  body {
    font-size: 12pt;
    line-height: 1.5;
    color: black;
  }
  
  a {
    color: black;
    text-decoration: underline;
  }
}