/* Data Science Analytical Handbook - Modern Design System */
/* Adapted from Datalake-Guide styling */

/* Import modern font families */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&family=JetBrains+Mono:wght@400;500;600&display=swap');

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

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

/* Design System Variables */
:root {
  /* Primary Brand Colors - Data Science Theme */
  --color-primary: #4F46E5;        /* Vibrant indigo */
  --color-primary-light: #818CF8;  /* Soft indigo */
  --color-primary-lighter: #C7D2FE; /* Pale indigo */
  --color-primary-dark: #3730A3;   /* Deep indigo */

  /* Secondary Accent Colors */
  --color-secondary: #EC4899;      /* Vibrant pink */
  --color-secondary-light: #F9A8D4; /* Soft pink */
  --color-accent: #F59E0B;         /* Warm amber */
  --color-accent-light: #FCD34D;   /* Bright yellow */

  /* Neutral Palette - Warmer Tones */
  --color-bg-primary: #FEFEFE;     /* Warm white */
  --color-bg-secondary: #F8FAFC;   /* Light gray-blue */
  --color-bg-tertiary: #F1F5F9;    /* Slightly darker gray-blue */
  --color-text-primary: #18181B;   /* Near-black for max contrast */
  --color-text-secondary: #27272A; /* Darker slate for better contrast */
  --color-text-tertiary: #71717A;  /* Medium slate */

  /* Success & Status Colors */
  --color-success: #10B981;        /* Emerald green */
  --color-warning: #F59E0B;        /* Amber */
  --color-error: #EF4444;          /* Red */
  --color-info: #3B82F6;           /* Blue */

  /* Gradients */
  --gradient-hero: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --gradient-card: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  --gradient-cta: linear-gradient(135deg, #EC4899 0%, #F59E0B 100%);

  /* Font Families */
  --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Monaco', 'Courier New', monospace;

  /* Font Sizes - Fluid Typography */
  --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --text-sm: clamp(0.875rem, 0.8rem + 0.375vw, 1rem);
  --text-base: clamp(1rem, 0.9rem + 0.5vw, 1.125rem);
  --text-lg: clamp(1.125rem, 1rem + 0.625vw, 1.25rem);
  --text-xl: clamp(1.25rem, 1.1rem + 0.75vw, 1.5rem);
  --text-2xl: clamp(1.5rem, 1.3rem + 1vw, 2rem);
  --text-3xl: clamp(1.875rem, 1.5rem + 1.5vw, 2.5rem);
  --text-4xl: clamp(2.25rem, 1.8rem + 2vw, 3rem);

  /* Line Heights */
  --leading-tight: 1.25;
  --leading-normal: 1.5;
  --leading-relaxed: 1.75;

  /* Font Weights */
  --font-light: 300;
  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;
  --font-extrabold: 800;

  /* Spacing Scale - 8px base */
  --space-1: 0.25rem;   /* 4px */
  --space-2: 0.5rem;    /* 8px */
  --space-3: 0.75rem;   /* 12px */
  --space-4: 1rem;      /* 16px */
  --space-5: 1.5rem;    /* 24px */
  --space-6: 2rem;      /* 32px */
  --space-8: 3rem;      /* 48px */
  --space-10: 4rem;     /* 64px */
  --space-12: 6rem;     /* 96px */
  --space-16: 8rem;     /* 128px */

  /* Border Radius */
  --radius-sm: 0.375rem;  /* 6px */
  --radius-md: 0.5rem;    /* 8px */
  --radius-lg: 0.75rem;   /* 12px */
  --radius-xl: 1rem;      /* 16px */
  --radius-2xl: 1.5rem;   /* 24px */
  --radius-full: 9999px;

  /* Shadows - Softer, More Elevated */
  --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 cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Dark Mode Palette */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg-primary: #0F172A;     /* Deep slate */
    --color-bg-secondary: #1E293B;   /* Slate */
    --color-bg-tertiary: #334155;    /* Medium slate */
    --color-text-primary: #F1F5F9;   /* Light */
    --color-text-secondary: #CBD5E1; /* Medium light */
    --color-text-tertiary: #94A3B8;  /* Muted */
  }
}

/* Manual theme override */
[data-theme="dark"] {
  --color-bg-primary: #0F172A;
  --color-bg-secondary: #1E293B;
  --color-bg-tertiary: #334155;
  --color-text-primary: #F1F5F9;
  --color-text-secondary: #CBD5E1;
  --color-text-tertiary: #94A3B8;
}

[data-theme="dark"] .site-header {
  background: var(--color-bg-primary);
  border-bottom-color: rgba(255, 255, 255, 0.1);
}

body {
    font-family: var(--font-primary);
    font-size: var(--text-base);
    line-height: var(--leading-normal);
    font-weight: var(--font-normal);
    color: var(--color-text-primary);
    background: var(--color-bg-primary);
    font-display: swap;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--space-6);
}

/* Header and Navigation */
.site-header {
    background: var(--color-bg-primary);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.06);
    box-shadow: var(--shadow-sm);
    padding: var(--space-4) 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: all var(--transition-base);
}

.site-header.scrolled {
    box-shadow: var(--shadow-lg);
    border-bottom-color: rgba(0, 0, 0, 0.1);
}

.main-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--space-6);
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--space-6);
}

.nav-brand a {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    text-decoration: none;
    font-size: var(--text-xl);
    font-weight: var(--font-bold);
    color: var(--color-primary);
    transition: transform var(--transition-fast);
    will-change: transform;
}

.nav-brand a:hover {
    transform: translateY(-2px);
}

.nav-brand i {
    font-size: var(--text-2xl);
    background: var(--gradient-cta);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: var(--space-2);
    margin: 0;
    padding: 0;
}

.nav-links a {
    position: relative;
    display: block;
    padding: var(--space-2) var(--space-4);
    color: var(--color-text-secondary);
    text-decoration: none;
    font-weight: var(--font-medium);
    font-size: var(--text-sm);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.nav-links a::before {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 0;
    height: 2px;
    background: var(--gradient-cta);
    transform: translateX(-50%);
    transition: width var(--transition-base);
}

.nav-links a:hover {
    color: var(--color-primary);
    background: var(--color-bg-secondary);
}

.nav-links a:hover::before {
    width: 80%;
}

.nav-links a.active {
    background: var(--color-primary-lighter);
    color: var(--color-primary-dark);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: var(--space-3);
}

.nav-actions .btn {
    padding: var(--space-3) var(--space-5);
    background: var(--gradient-cta);
    color: white;
    border: none;
    border-radius: var(--radius-lg);
    font-weight: var(--font-semibold);
    font-size: var(--text-sm);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
    cursor: pointer;
}

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

.theme-toggle {
    background: none;
    border: 2px solid var(--color-text-secondary);
    border-radius: var(--radius-full);
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-base);
    color: var(--color-text-secondary);
    font-size: var(--text-lg);
}

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

/* Mobile Navigation Toggle */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--color-text-secondary);
    font-size: var(--text-xl);
    cursor: pointer;
    padding: var(--space-2);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.nav-toggle:hover {
    background: var(--color-bg-secondary);
    color: var(--color-primary);
}

/* Main Content */
.main-content {
    min-height: calc(100vh - 300px);
}

/* Content Styling */
.content {
    max-width: 900px;
    margin: 0 auto;
    padding: var(--space-8) var(--space-4);
}

.content h1,
.content h2,
.content h3,
.content h4,
.content h5,
.content h6 {
    font-weight: var(--font-bold);
    line-height: var(--leading-tight);
    color: var(--color-text-primary);
    margin-top: var(--space-8);
    margin-bottom: var(--space-4);
}

.content h1 {
    font-size: var(--text-3xl);
    color: var(--color-text-primary);
    padding-bottom: var(--space-2);
    border-bottom: 2px solid var(--color-bg-tertiary);
}

.content h2 {
    font-size: var(--text-2xl);
    color: var(--color-primary-dark);
    padding-bottom: var(--space-2);
    border-bottom: 1px solid var(--color-bg-tertiary);
}

.content h3 {
    font-size: var(--text-xl);
    color: var(--color-primary-dark);
}

.content h4 {
    font-size: var(--text-lg);
    color: var(--color-text-primary);
}

.content p {
    margin-bottom: var(--space-5);
    line-height: var(--leading-relaxed);
    color: var(--color-text-secondary);
}

.content a {
    color: var(--color-primary);
    text-decoration: none;
    border-bottom: 2px solid var(--color-primary-lighter);
    transition: all var(--transition-fast);
    font-weight: var(--font-medium);
}

.content a:hover {
    color: var(--color-primary-dark);
    border-bottom-color: var(--color-primary);
}

.content code {
    padding: var(--space-1) var(--space-2);
    background: var(--color-bg-secondary);
    border: 1px solid rgba(0, 0, 0, 0.06);
    border-radius: var(--radius-sm);
    font-family: var(--font-mono);
    font-size: 0.9em;
    color: var(--color-secondary);
    font-weight: var(--font-medium);
}

.content pre {
    position: relative;
    padding: var(--space-6);
    background: var(--color-bg-tertiary);
    border: 1px solid rgba(0, 0, 0, 0.06);
    border-radius: var(--radius-lg);
    overflow-x: auto;
    margin: var(--space-6) 0;
    box-shadow: var(--shadow-md);
}

.content pre code {
    padding: 0;
    background: none;
    border: none;
    color: var(--color-text-primary);
    font-size: var(--text-sm);
}

.content ul,
.content ol {
    margin-bottom: var(--space-5);
    padding-left: var(--space-6);
}

.content li {
    margin-bottom: var(--space-2);
    line-height: var(--leading-relaxed);
    color: var(--color-text-secondary);
}

/* Tables */
.content table {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0;
    margin: var(--space-6) 0;
    background: var(--color-bg-primary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

.content th {
    padding: var(--space-4);
    background: var(--gradient-hero);
    color: white;
    font-weight: var(--font-semibold);
    font-size: var(--text-sm);
    text-align: left;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.content td {
    padding: var(--space-4);
    border-bottom: 1px solid var(--color-bg-tertiary);
    color: var(--color-text-secondary);
    font-size: var(--text-sm);
}

.content tr:last-child td {
    border-bottom: none;
}

.content tr:hover {
    background: var(--color-bg-secondary);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-5);
    border-radius: var(--radius-lg);
    text-decoration: none;
    font-weight: var(--font-semibold);
    font-size: var(--text-sm);
    transition: all var(--transition-base);
    border: none;
    cursor: pointer;
}

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

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

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

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

/* Hero Section */
.hero {
    background: var(--gradient-hero);
    color: white;
    padding: var(--space-16) 0 var(--space-12) 0;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 800px;
    margin: 0 auto;
    padding: 0 var(--space-6);
}

.hero-title {
    font-family: var(--font-primary);
    font-size: var(--text-4xl);
    font-weight: 900;
    line-height: var(--leading-tight);
    margin-bottom: var(--space-6);
    color: white;
    letter-spacing: -0.02em;
}

.hero-subtitle {
    font-family: var(--font-primary);
    font-size: var(--text-xl);
    font-weight: 300;
    line-height: var(--leading-relaxed);
    margin-bottom: var(--space-8);
    color: rgba(255, 255, 255, 0.9);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-badges {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--space-3);
    margin-bottom: var(--space-10);
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-2) var(--space-4);
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-full);
    font-size: var(--text-sm);
    font-weight: var(--font-medium);
    color: white;
    text-decoration: none;
    transition: all var(--transition-fast);
}

.hero-badge:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

.hero-cta {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-4) var(--space-8);
    background: white;
    color: var(--color-primary-dark);
    text-decoration: none;
    font-weight: var(--font-semibold);
    font-size: var(--text-base);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-xl);
    transition: all var(--transition-base);
}

.hero-cta:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-2xl);
}

/* Feature Grid */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-8);
    padding: var(--space-16) var(--space-6);
    max-width: 1400px;
    margin: 0 auto;
}

.feature-card {
    background: var(--color-bg-primary);
    border: 1px solid var(--color-bg-tertiary);
    border-radius: var(--radius-xl);
    padding: var(--space-8);
    text-align: center;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-sm);
    position: relative;
    overflow: hidden;
    text-decoration: none;
}

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

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

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--color-primary-lighter);
}

.feature-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto var(--space-6);
    background: var(--color-bg-secondary);
    border-radius: var(--radius-xl);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--text-3xl);
    color: var(--color-primary);
}

.feature-title {
    font-size: var(--text-xl);
    font-weight: var(--font-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--space-4);
}

.feature-description {
    color: var(--color-text-secondary);
    line-height: var(--leading-relaxed);
    margin-bottom: var(--space-6);
}

.feature-link {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    color: var(--color-primary);
    text-decoration: none;
    font-weight: var(--font-semibold);
    transition: all var(--transition-fast);
}

.feature-link:hover {
    color: var(--color-primary-dark);
    transform: translateX(4px);
}

/* Resources Grid (for home page cards) */
.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-6);
    padding: var(--space-8) var(--space-6);
    max-width: 1200px;
    margin: 0 auto;
}

.resource-card {
    background: var(--color-bg-primary);
    border: 1px solid var(--color-bg-tertiary);
    border-radius: var(--radius-lg);
    padding: var(--space-6);
    text-decoration: none;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-sm);
    display: block;
}

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

.resource-card .icon-container {
    font-size: var(--text-3xl);
    margin-bottom: var(--space-4);
}

.resource-card h3 {
    font-size: var(--text-lg);
    font-weight: var(--font-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--space-3);
}

.resource-card p {
    color: var(--color-text-secondary);
    line-height: var(--leading-relaxed);
    font-size: var(--text-sm);
    margin: 0;
}

/* Stats Section */
.stats-section {
    background: var(--color-bg-secondary);
    padding: var(--space-12) 0;
    margin: var(--space-16) 0;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--space-8);
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 var(--space-6);
}

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

.stat-number {
    font-size: var(--text-4xl);
    font-weight: var(--font-extrabold);
    background: var(--gradient-hero);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: var(--leading-tight);
    margin-bottom: var(--space-2);
}

.stat-label {
    font-size: var(--text-sm);
    color: var(--color-text-secondary);
    font-weight: var(--font-medium);
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

/* Call to Action Section */
.cta-section {
    background: var(--gradient-hero);
    color: white;
    padding: var(--space-16) 0;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.cta-content {
    position: relative;
    z-index: 2;
    max-width: 600px;
    margin: 0 auto;
    padding: 0 var(--space-6);
}

.cta-title {
    font-size: var(--text-3xl);
    font-weight: var(--font-bold);
    margin-bottom: var(--space-4);
}

.cta-description {
    font-size: var(--text-lg);
    margin-bottom: var(--space-8);
    opacity: 0.9;
    line-height: var(--leading-relaxed);
}

.cta-buttons {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--space-4);
}

/* Button Group */
.button-group {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--space-4);
    margin-top: var(--space-6);
}

.button {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-6);
    border-radius: var(--radius-lg);
    text-decoration: none;
    font-weight: var(--font-semibold);
    font-size: var(--text-sm);
    transition: all var(--transition-base);
    border: 2px solid rgba(255, 255, 255, 0.3);
    color: white;
}

.button:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: translateY(-2px);
}

.button.primary-button {
    background: white;
    color: var(--color-primary-dark);
    border-color: white;
}

.button.primary-button:hover {
    background: var(--color-bg-secondary);
}

/* Header (legacy support) */
.header {
    background: var(--gradient-hero);
    color: white;
    text-align: center;
    padding: var(--space-12) var(--space-6);
    margin-bottom: var(--space-8);
}

.header h1 {
    font-size: var(--text-4xl);
    font-weight: 900;
    margin-bottom: var(--space-4);
}

.header p {
    font-size: var(--text-xl);
    opacity: 0.9;
    max-width: 600px;
    margin: 0 auto;
}

/* Cards (legacy support) */
.card {
    background: var(--color-bg-primary);
    border: 1px solid var(--color-bg-tertiary);
    border-radius: var(--radius-lg);
    padding: var(--space-6);
    margin-bottom: var(--space-6);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-base);
}

.card:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--color-primary-lighter);
}

.card h4 {
    font-size: var(--text-lg);
    font-weight: var(--font-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--space-4);
}

.card p {
    color: var(--color-text-secondary);
    line-height: var(--leading-relaxed);
    margin-bottom: var(--space-4);
}

.card ul, .card ol {
    margin-bottom: var(--space-4);
    padding-left: var(--space-6);
}

.card li {
    color: var(--color-text-secondary);
    line-height: var(--leading-relaxed);
    margin-bottom: var(--space-2);
}

/* Navigation Buttons */
.navigation-buttons {
    display: flex;
    justify-content: center;
    gap: var(--space-4);
    margin-top: var(--space-8);
    padding-top: var(--space-6);
    border-top: 1px solid var(--color-bg-tertiary);
}

.navigation-buttons a {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-6);
    background: var(--color-primary);
    color: white;
    text-decoration: none;
    border-radius: var(--radius-lg);
    font-weight: var(--font-semibold);
    transition: all var(--transition-base);
}

.navigation-buttons a:hover {
    background: var(--color-primary-dark);
    transform: translateY(-2px);
}

/* Breadcrumb */
.breadcrumb {
    padding: var(--space-4) var(--space-6);
    font-size: var(--text-sm);
    color: var(--color-text-tertiary);
    max-width: 1200px;
    margin: 0 auto;
}

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

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

.breadcrumb span {
    margin: 0 var(--space-2);
}

/* Section Title */
.section-title {
    font-size: var(--text-2xl);
    font-weight: var(--font-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--space-6);
    padding-bottom: var(--space-3);
    border-bottom: 2px solid var(--color-primary-lighter);
}

/* Code Block */
.code-block {
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-bg-tertiary);
    border-radius: var(--radius-lg);
    padding: var(--space-5);
    margin: var(--space-4) 0;
    overflow-x: auto;
}

.code-block pre,
.code-block code {
    font-family: var(--font-mono);
    font-size: var(--text-sm);
    color: var(--color-text-primary);
}

/* Sidebar */
.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: 280px;
    height: 100vh;
    background: var(--color-bg-primary);
    border-right: 1px solid var(--color-bg-tertiary);
    padding: var(--space-6);
    overflow-y: auto;
    z-index: 100;
}

.sidebar h2 {
    font-size: var(--text-lg);
    font-weight: var(--font-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--space-6);
    padding-bottom: var(--space-3);
    border-bottom: 2px solid var(--color-primary);
}

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

.nav-list > li {
    margin-bottom: var(--space-2);
}

.nav-list > li > a {
    display: block;
    padding: var(--space-3) var(--space-4);
    color: var(--color-text-secondary);
    text-decoration: none;
    border-radius: var(--radius-md);
    font-weight: var(--font-medium);
    transition: all var(--transition-fast);
}

.nav-list > li > a:hover,
.nav-list > li > a.active {
    background: var(--color-primary-lighter);
    color: var(--color-primary-dark);
}

.nav-list ul {
    list-style: none;
    padding-left: var(--space-4);
    margin-top: var(--space-2);
}

.nav-list ul li a {
    display: block;
    padding: var(--space-2) var(--space-3);
    color: var(--color-text-tertiary);
    text-decoration: none;
    font-size: var(--text-sm);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.nav-list ul li a:hover {
    color: var(--color-primary);
    background: var(--color-bg-secondary);
}

/* Main content when sidebar is present - using sibling selector */
.sidebar ~ .main-content {
    margin-left: 280px;
}

/* Footer */
.site-footer {
    background: var(--color-text-primary);
    color: var(--color-text-tertiary);
    padding: var(--space-12) var(--space-6) var(--space-6);
    margin-top: var(--space-16);
}

.footer-content {
    max-width: 1400px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--space-8);
    margin-bottom: var(--space-8);
}

.footer-section h4 {
    color: white;
    font-size: var(--text-lg);
    font-weight: var(--font-bold);
    margin-bottom: var(--space-4);
    position: relative;
    padding-bottom: var(--space-2);
}

.footer-section h4::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 40px;
    height: 3px;
    background: var(--gradient-cta);
    border-radius: var(--radius-full);
}

.footer-section ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.footer-section li {
    margin-bottom: var(--space-3);
}

.footer-section a {
    color: var(--color-text-tertiary);
    text-decoration: none;
    transition: all var(--transition-fast);
    display: inline-block;
}

.footer-section a:hover {
    color: white;
    transform: translateX(4px);
}

.footer-bottom {
    max-width: 1400px;
    margin: 0 auto;
    padding-top: var(--space-6);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    text-align: center;
    font-size: var(--text-sm);
}

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

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

/* Simple Footer (legacy) */
footer {
    max-width: 1200px;
    margin: var(--space-16) auto 0;
    padding: var(--space-8) var(--space-6);
    border-top: 1px solid var(--color-bg-tertiary);
    text-align: center;
    color: var(--color-text-tertiary);
    font-size: var(--text-sm);
}

/* Accessibility */
.skip-link {
    position: absolute;
    top: -40px;
    left: 6px;
    background: var(--color-primary);
    color: white;
    padding: var(--space-2) var(--space-4);
    text-decoration: none;
    z-index: 10000;
    transition: top var(--transition-fast);
}

.skip-link:focus {
    top: 6px;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

*:focus-visible {
    outline: 3px solid var(--color-primary);
    outline-offset: 2px;
    border-radius: var(--radius-sm);
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* Responsive Design */
@media (max-width: 1024px) {
    .sidebar {
        position: static;
        width: 100%;
        height: auto;
        border-right: none;
        border-bottom: 1px solid var(--color-bg-tertiary);
    }

    .sidebar ~ .main-content {
        margin-left: 0;
    }
}

@media (max-width: 768px) {
    :root {
        --space-6: 1.5rem;
        --space-8: 2rem;
        --space-10: 3rem;
        --space-12: 4rem;
    }

    .main-nav {
        flex-wrap: wrap;
        gap: var(--space-4);
    }

    .nav-toggle {
        display: block;
    }

    .nav-links {
        display: none;
        width: 100%;
        flex-direction: column;
        gap: 0;
    }

    .nav-links.active {
        display: flex;
    }

    .nav-links a {
        width: 100%;
        text-align: center;
        padding: var(--space-3) var(--space-4);
        border-bottom: 1px solid var(--color-bg-tertiary);
    }

    .hero {
        padding: var(--space-12) 0 var(--space-8) 0;
    }

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

    .features-grid,
    .resources-grid {
        grid-template-columns: 1fr;
        gap: var(--space-6);
        padding: var(--space-8) var(--space-4);
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-6);
    }

    .content {
        padding: var(--space-6) var(--space-4);
    }

    .navigation-buttons {
        flex-direction: column;
        align-items: center;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: var(--space-6);
    }
}

@media (max-width: 480px) {
    .hero-badges {
        flex-direction: column;
        align-items: center;
    }

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

    .button-group {
        flex-direction: column;
        align-items: center;
    }

    .cta-buttons {
        flex-direction: column;
        align-items: center;
    }
}

/* Tracks and Skills Styles */
.tracks-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.track-card {
    background: var(--color-bg-primary);
    border: 1px solid var(--color-border);
    border-radius: 0.75rem;
    padding: 1.5rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.track-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

.track-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.track-icon {
    font-size: 2rem;
    color: var(--color-primary);
}

.track-meta {
    text-align: right;
}

.track-duration {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    font-weight: 500;
}

.track-difficulty {
    display: inline-block;
    padding: 0.25rem 0.5rem;
    border-radius: 0.25rem;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    margin-top: 0.25rem;
}

.track-difficulty.beginner {
    background: var(--color-success);
    color: white;
}

.track-difficulty.intermediate {
    background: var(--color-warning);
    color: white;
}

.track-difficulty.advanced {
    background: var(--color-error);
    color: white;
}

.track-card h3 {
    margin: 0 0 0.5rem 0;
    color: var(--color-text-primary);
}

.track-description {
    color: var(--color-text-secondary);
    margin-bottom: 1rem;
    line-height: 1.5;
}

.track-audience {
    font-size: 0.875rem;
    color: var(--color-text-tertiary);
    margin-bottom: 1rem;
    font-style: italic;
}

.track-content h4 {
    margin: 1rem 0 0.5rem 0;
    font-size: 1rem;
    color: var(--color-text-primary);
}

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

.track-modules li {
    padding: 0.25rem 0;
    font-size: 0.875rem;
    color: var(--color-text-secondary);
}

.track-modules a {
    color: var(--color-primary);
    text-decoration: none;
}

.track-modules a:hover {
    text-decoration: underline;
}

.track-actions {
    margin-top: 1.5rem;
    display: flex;
    gap: 0.5rem;
}

.track-start-btn {
    flex: 1;
}

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

.track-progress-btn.has-progress {
    background: var(--color-success);
    color: white;
    border-color: var(--color-success);
}

.tracks-info {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin: 3rem 0;
}

.info-card {
    background: var(--color-bg-secondary);
    padding: 1.5rem;
    border-radius: 0.5rem;
    border-left: 4px solid var(--color-primary);
}

.info-card h3 {
    margin: 0 0 1rem 0;
    color: var(--color-text-primary);
}

.info-card ul {
    margin: 0;
    padding-left: 1.5rem;
}

.info-card li {
    margin-bottom: 0.5rem;
    color: var(--color-text-secondary);
}

/* Skills Matrix Styles */
.skills-overview {
    background: var(--color-bg-secondary);
    padding: 2rem;
    border-radius: 0.75rem;
    margin: 2rem 0;
}

.skills-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.stat-card {
    text-align: center;
    padding: 1rem;
    background: var(--color-bg-primary);
    border-radius: 0.5rem;
    border: 1px solid var(--color-border);
}

.stat-number {
    font-size: 2rem;
    font-weight: 700;
    color: var(--color-primary);
    display: block;
}

.stat-label {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    margin-top: 0.5rem;
}

.skills-cloud {
    margin: 2rem 0;
}

.skills-cloud h3 {
    margin-bottom: 1rem;
    color: var(--color-text-primary);
}

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

.skill-tag {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: var(--color-bg-primary);
    border: 1px solid var(--color-border);
    border-radius: 2rem;
    text-decoration: none;
    color: var(--color-text-primary);
    font-size: 0.875rem;
    transition: all 0.2s ease;
}

.skill-tag:hover {
    background: var(--color-primary);
    color: white;
    transform: translateY(-1px);
}

.tag-count {
    background: var(--color-primary-light);
    color: var(--color-primary-dark);
    padding: 0.125rem 0.375rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 600;
}

.skill-tag:hover .tag-count {
    background: rgba(255, 255, 255, 0.2);
    color: white;
}

.skill-section {
    margin: 3rem 0;
    padding: 2rem;
    background: var(--color-bg-secondary);
    border-radius: 0.75rem;
    border: 1px solid var(--color-border);
}

.skill-section h3 {
    margin: 0 0 1.5rem 0;
    color: var(--color-text-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.skill-count {
    font-size: 0.875rem;
    color: var(--color-text-tertiary);
    font-weight: normal;
}

.skill-difficulty-tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--color-border);
}

.tab-btn {
    padding: 0.75rem 1.5rem;
    background: transparent;
    border: 1px solid var(--color-border);
    border-bottom: none;
    border-radius: 0.5rem 0.5rem 0 0;
    cursor: pointer;
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    transition: all 0.2s ease;
}

.tab-btn.active {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}

.tab-btn:hover:not(.active) {
    background: var(--color-bg-primary);
    color: var(--color-text-primary);
}

.skill-content-tabs .tab-content {
    display: none;
}

.skill-content-tabs .tab-content.active {
    display: block;
}

.skill-modules {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1rem;
}

.skill-module-card {
    background: var(--color-bg-primary);
    border: 1px solid var(--color-border);
    border-radius: 0.5rem;
    padding: 1rem;
    transition: box-shadow 0.2s ease;
}

.skill-module-card:hover {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.module-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 0.5rem;
}

.module-header h4 {
    margin: 0;
    font-size: 1rem;
    flex: 1;
}

.module-header h4 a {
    color: var(--color-text-primary);
    text-decoration: none;
}

.module-header h4 a:hover {
    color: var(--color-primary);
}

.module-time {
    font-size: 0.75rem;
    color: var(--color-text-tertiary);
    white-space: nowrap;
    margin-left: 0.5rem;
}

.skill-module-card p {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    margin: 0.5rem 0;
    line-height: 1.4;
}

.module-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 1rem;
}

.module-track {
    font-size: 0.75rem;
    color: var(--color-primary);
    font-weight: 500;
}

.mark-complete-btn {
    padding: 0.375rem 0.75rem;
    border: 1px solid var(--color-border);
    background: transparent;
    color: var(--color-text-primary);
    border-radius: 0.25rem;
    cursor: pointer;
    font-size: 0.75rem;
    transition: all 0.2s ease;
}

.mark-complete-btn:hover {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}

.mark-complete-btn.completed {
    background: var(--color-success);
    color: white;
    border-color: var(--color-success);
}

/* Modal Styles */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.modal-overlay > div {
    background: var(--color-bg-primary);
    padding: 2rem;
    border-radius: 0.75rem;
    max-width: 500px;
    width: 90%;
    max-height: 80vh;
    overflow-y: auto;
}

.progress-modal h3 {
    margin: 0 0 1.5rem 0;
    color: var(--color-text-primary);
}

.progress-modules {
    margin-bottom: 1.5rem;
}

.progress-item {
    display: flex;
    align-items: center;
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--color-border);
}

.progress-item:last-child {
    border-bottom: none;
}

.progress-item.completed {
    color: var(--color-success);
}

.progress-item input[type="checkbox"] {
    margin-right: 0.75rem;
}

.checkmark {
    width: 20px;
    height: 20px;
    border: 2px solid var(--color-border);
    border-radius: 3px;
    display: inline-block;
    position: relative;
    margin-right: 0.5rem;
    cursor: pointer;
}

.progress-item input[type="checkbox"]:checked + .checkmark {
    background: var(--color-success);
    border-color: var(--color-success);
}

.progress-item input[type="checkbox"]:checked + .checkmark::after {
    content: '✓';
    position: absolute;
    top: -2px;
    left: 2px;
    color: white;
    font-size: 14px;
    font-weight: bold;
}

.page-progress {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 2rem;
    padding: 1.5rem;
    background: var(--color-bg-secondary);
    border-radius: 0.5rem;
    border: 1px solid var(--color-border);
}

.page-time,
.page-difficulty {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.875rem;
    font-weight: 500;
}

.page-time {
    color: var(--color-text-secondary);
}

.page-difficulty.beginner {
    color: var(--color-success);
}

.page-difficulty.intermediate {
    color: var(--color-warning);
}

.skill-section.highlight {
    background: var(--color-bg-secondary);
    border-radius: 0.5rem;
}

.page-difficulty.advanced {
    color: var(--color-error);
}

#mark-complete-btn.completed {
    background: var(--color-success);
    border-color: var(--color-success);
}

/* Search Styles */
.search-container {
    position: relative;
    display: flex;
    align-items: center;
    margin-right: 1rem;
}

#search-input {
    padding: 0.5rem 2.5rem 0.5rem 1rem;
    border: 2px solid var(--color-border);
    border-radius: 0.5rem;
    background: var(--color-bg-primary);
    color: var(--color-text-primary);
    font-size: 0.875rem;
    width: 200px;
    transition: all 0.2s ease;
}

#search-input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.search-icon {
    position: absolute;
    right: 0.75rem;
    color: var(--color-text-tertiary);
    pointer-events: none;
}

.search-results {
    position: absolute;
    top: 100%;
    right: 0;
    width: 300px;
    max-height: 400px;
    background: var(--color-bg-primary);
    border: 1px solid var(--color-border);
    border-radius: 0.5rem;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
    z-index: 1000;
    overflow-y: auto;
    margin-top: 0.5rem;
}

.search-results-header {
    padding: 1rem;
    border-bottom: 1px solid var(--color-border);
}

.search-results-header h4 {
    margin: 0;
    font-size: 1rem;
    color: var(--color-text-primary);
}

.search-results ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

.search-results li {
    border-bottom: 1px solid var(--color-border);
}

.search-results li:last-child {
    border-bottom: none;
}

.search-results a {
    display: block;
    padding: 1rem;
    text-decoration: none;
    color: var(--color-text-primary);
    transition: background-color 0.2s ease;
}

.search-results a:hover {
    background: var(--color-bg-secondary);
}

.search-results strong {
    display: block;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.search-results p {
    font-size: 0.875rem;
    color: var(--color-text-tertiary);
    margin: 0;
    line-height: 1.4;
}

/* Print Styles */
@media print {
    .site-header,
    .sidebar,
    .site-footer,
    .navigation-buttons,
    .cta-section {
        display: none;
    }

    .content {
        max-width: none;
    }

    body {
        color: black;
        background: white;
    }
}

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

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