/* DesignVerse — Main Stylesheet
   Design System + 2025/2026 Trending Effects
   =========================================== */

/* ============================================
   CUSTOM PROPERTIES (Design Tokens)
   ============================================ */
:root {
  /* Typography */
  --font-display: 'Instrument Serif', 'Georgia', serif;
  --font-body: 'Satoshi', 'system-ui', -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  /* Type Scale */
  --text-xs: clamp(0.7rem, 0.65rem + 0.25vw, 0.75rem);
  --text-sm: clamp(0.8rem, 0.75rem + 0.25vw, 0.875rem);
  --text-base: clamp(0.95rem, 0.9rem + 0.25vw, 1.05rem);
  --text-lg: clamp(1.1rem, 1rem + 0.5vw, 1.25rem);
  --text-xl: clamp(1.25rem, 1.1rem + 0.75vw, 1.5rem);
  --text-2xl: clamp(1.5rem, 1.2rem + 1.5vw, 2rem);
  --text-3xl: clamp(1.8rem, 1.4rem + 2vw, 2.75rem);
  --text-4xl: clamp(2.2rem, 1.6rem + 3vw, 3.75rem);
  --text-5xl: clamp(2.8rem, 1.8rem + 5vw, 5rem);

  /* Colors — Light Theme (warm, refined) */
  --color-bg: #FAFAF8;
  --color-bg-warm: #F5F3EF;
  --color-bg-card: #FFFFFF;
  --color-bg-card-hover: #FEFEFE;
  --color-bg-code: #F5F3EF;
  --color-bg-accent: #EEF0FF;

  --color-text: #1A1A1A;
  --color-text-secondary: #555555;
  --color-text-tertiary: #8A8A8A;
  --color-text-muted: #ABABAB;

  --color-border: #E8E6E1;
  --color-border-light: #F0EDE8;
  --color-border-hover: #D0CEC9;

  --color-primary: #4F46E5;
  --color-primary-light: #EEF0FF;
  --color-primary-dark: #3730A3;
  --color-primary-glow: rgba(79, 70, 229, 0.15);

  --color-accent-1: #EC4899;
  --color-accent-2: #14B8A6;
  --color-accent-3: #F59E0B;
  --color-accent-4: #EF4444;

  /* Section Colors */
  --section-foundations: #6366F1;
  --section-ui: #EC4899;
  --section-ux: #14B8A6;
  --section-saas: #F59E0B;
  --section-product: #EF4444;
  --section-cx: #8B5CF6;
  --section-dev: #06B6D4;
  --section-career: #10B981;
  --section-advanced: #F97316;
  --section-business: #64748B;

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;
  --space-32: 8rem;

  /* Shadows (layered, warm) */
  --shadow-xs: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.04), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.06), 0 2px 4px rgba(0,0,0,0.04);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.08), 0 4px 8px rgba(0,0,0,0.04);
  --shadow-xl: 0 16px 48px rgba(0,0,0,0.1), 0 8px 16px rgba(0,0,0,0.04);
  --shadow-glow: 0 0 40px var(--color-primary-glow);

  /* Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-2xl: 32px;
  --radius-full: 9999px;

  /* Motion */
  --ease-out: cubic-bezier(0.0, 0.0, 0.2, 1.0);
  --ease-in: cubic-bezier(0.4, 0.0, 1.0, 1.0);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
  --ease-smooth: cubic-bezier(0.4, 0.0, 0.2, 1.0);

  --duration-fast: 150ms;
  --duration-normal: 250ms;
  --duration-slow: 400ms;

  /* Layout */
  --max-width: 1280px;
  --max-width-narrow: 720px;
  --max-width-wide: 1440px;
  --sidebar-width: 260px;
  --nav-height: 64px;
}

/* ============================================
   RESET & BASE
   ============================================ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-padding-top: calc(var(--nav-height) + 2rem);
}

body {
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.65;
  color: var(--color-text);
  background: var(--color-bg);
  overflow-x: hidden;
}

img, picture, video, svg { display: block; max-width: 100%; }
input, button, textarea, select { font: inherit; }
a { color: inherit; text-decoration: none; }
button { cursor: pointer; border: none; background: none; }
ul, ol { list-style: none; }

::selection {
  background: var(--color-primary);
  color: white;
}

/* ============================================
   TYPOGRAPHY
   ============================================ */
.font-display { font-family: var(--font-display); }
.font-body { font-family: var(--font-body); }
.font-mono { font-family: var(--font-mono); }

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  line-height: 1.15;
  font-weight: 400;
  letter-spacing: -0.02em;
  color: var(--color-text);
}

h1 { font-size: var(--text-5xl); }
h2 { font-size: var(--text-3xl); margin-bottom: var(--space-4); }
h3 { font-size: var(--text-2xl); margin-bottom: var(--space-3); }
h4 { font-size: var(--text-xl); }

p { margin-bottom: var(--space-4); max-width: 65ch; }
p.lead { font-size: var(--text-lg); color: var(--color-text-secondary); line-height: 1.7; }

/* ============================================
   NAVIGATION
   ============================================ */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  height: var(--nav-height);
  background: rgba(250, 250, 248, 0.85);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid transparent;
  transition: border-color var(--duration-normal) ease, box-shadow var(--duration-normal) ease;
}

.nav.scrolled {
  border-bottom-color: var(--color-border-light);
  box-shadow: 0 1px 12px rgba(0,0,0,0.04);
}

.nav-inner {
  max-width: var(--max-width-wide);
  margin: 0 auto;
  padding: 0 var(--space-6);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  color: var(--color-text);
  display: flex;
  align-items: center;
  gap: var(--space-2);
  transition: opacity var(--duration-fast) ease;
}

.nav-logo:hover { opacity: 0.7; }

.nav-logo-icon {
  width: 32px; height: 32px;
  background: var(--color-primary);
  border-radius: var(--radius-sm);
  display: grid; place-items: center;
  color: white; font-weight: 600;
  font-family: var(--font-body);
  font-size: 14px;
  transform: rotate(-3deg);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.nav-link {
  padding: var(--space-2) var(--space-3);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  border-radius: var(--radius-sm);
  transition: color var(--duration-fast) ease, background var(--duration-fast) ease;
  position: relative;
}

.nav-link:hover {
  color: var(--color-text);
  background: var(--color-bg-warm);
}

.nav-link.active {
  color: var(--color-primary);
  background: var(--color-primary-light);
}

.nav-search-btn {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  background: var(--color-bg-warm);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
  transition: all var(--duration-fast) ease;
  cursor: pointer;
}

.nav-search-btn:hover {
  border-color: var(--color-border-hover);
  box-shadow: var(--shadow-sm);
}

.nav-search-btn kbd {
  font-size: 0.7rem;
  padding: 2px 6px;
  background: white;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-family: var(--font-body);
}

.nav-mobile-toggle {
  display: none;
  width: 40px; height: 40px;
  border-radius: var(--radius-sm);
  align-items: center;
  justify-content: center;
  color: var(--color-text);
}

@media (max-width: 768px) {
  .nav-links { display: none; }
  .nav-search-btn kbd { display: none; }
  .nav-mobile-toggle { display: flex; }
  
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: fixed;
    top: var(--nav-height);
    left: 0; right: 0; bottom: 0;
    background: var(--color-bg);
    padding: var(--space-6);
    gap: var(--space-2);
    z-index: 999;
    animation: slideDown 300ms var(--ease-out);
  }
}

/* ============================================
   HERO SECTION
   ============================================ */
.hero {
  padding: calc(var(--nav-height) + var(--space-20)) var(--space-6) var(--space-20);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%; left: -50%;
  width: 200%; height: 200%;
  background:
    radial-gradient(ellipse at 20% 50%, rgba(99, 102, 241, 0.06) 0%, transparent 50%),
    radial-gradient(ellipse at 80% 20%, rgba(236, 72, 153, 0.04) 0%, transparent 50%),
    radial-gradient(ellipse at 50% 80%, rgba(20, 184, 166, 0.04) 0%, transparent 50%);
  animation: heroGlow 20s ease-in-out infinite alternate;
  pointer-events: none;
}

@keyframes heroGlow {
  0% { transform: translate(0, 0) scale(1); }
  100% { transform: translate(-3%, -3%) scale(1.05); }
}

.hero-inner {
  max-width: 900px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-1) var(--space-4);
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-8);
  animation: fadeInUp 600ms var(--ease-out) both;
}

.hero-badge-dot {
  width: 6px; height: 6px;
  background: var(--color-accent-2);
  border-radius: 50%;
  animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.6; transform: scale(1.5); }
}

.hero h1 {
  font-size: var(--text-5xl);
  line-height: 1.05;
  margin-bottom: var(--space-6);
  animation: fadeInUp 600ms var(--ease-out) 100ms both;
}

.hero h1 em {
  font-style: italic;
  color: var(--color-primary);
  position: relative;
}

.hero h1 em::after {
  content: '';
  position: absolute;
  bottom: 0.05em; left: 0; right: 0;
  height: 0.12em;
  background: var(--color-primary);
  opacity: 0.2;
  border-radius: 2px;
}

.hero-subtitle {
  font-size: var(--text-lg);
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto var(--space-10);
  line-height: 1.7;
  animation: fadeInUp 600ms var(--ease-out) 200ms both;
}

.hero-cta-group {
  display: flex;
  gap: var(--space-4);
  justify-content: center;
  flex-wrap: wrap;
  animation: fadeInUp 600ms var(--ease-out) 300ms both;
}

/* ============================================
   BUTTONS
   ============================================ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-weight: 600;
  font-size: var(--text-sm);
  border-radius: var(--radius-full);
  transition: all var(--duration-fast) var(--ease-smooth);
  position: relative;
  overflow: hidden;
}

.btn-lg {
  padding: var(--space-4) var(--space-8);
  font-size: var(--text-base);
}

.btn-primary {
  background: var(--color-text);
  color: var(--color-bg);
  box-shadow: var(--shadow-sm);
}

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

.btn-primary:active {
  transform: translateY(0);
}

.btn-secondary {
  background: var(--color-bg-card);
  color: var(--color-text);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover {
  border-color: var(--color-border-hover);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.btn-ghost {
  color: var(--color-text-secondary);
  padding: var(--space-2) var(--space-4);
}

.btn-ghost:hover {
  color: var(--color-text);
  background: var(--color-bg-warm);
}

/* Button arrow animation */
.btn .arrow {
  transition: transform var(--duration-fast) var(--ease-spring);
}
.btn:hover .arrow {
  transform: translateX(4px);
}

/* ============================================
   STATS BAR
   ============================================ */
.stats-bar {
  display: flex;
  justify-content: center;
  gap: var(--space-12);
  padding: var(--space-12) var(--space-6);
  flex-wrap: wrap;
}

.stat {
  text-align: center;
  animation: fadeInUp 600ms var(--ease-out) both;
}

.stat-number {
  font-family: var(--font-display);
  font-size: var(--text-3xl);
  color: var(--color-text);
  line-height: 1;
  margin-bottom: var(--space-1);
}

.stat-label {
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ============================================
   SECTION HEADER
   ============================================ */
.section-header {
  text-align: center;
  max-width: 700px;
  margin: 0 auto var(--space-16);
  padding: 0 var(--space-6);
}

.section-label {
  font-size: var(--text-sm);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-primary);
  margin-bottom: var(--space-3);
}

.section-header h2 {
  margin-bottom: var(--space-4);
}

.section-header p {
  color: var(--color-text-secondary);
  margin: 0 auto;
}

/* ============================================
   TOPIC GRID (Section Cards)
   ============================================ */
.topics-section {
  padding: var(--space-24) var(--space-6);
}

.topics-grid {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: var(--space-6);
}

.topic-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  position: relative;
  overflow: hidden;
  transition: all var(--duration-normal) var(--ease-smooth);
  cursor: pointer;
}

.topic-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: var(--card-color, var(--color-primary));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--duration-slow) var(--ease-spring);
}

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

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

.topic-card-icon {
  width: 48px; height: 48px;
  border-radius: var(--radius-md);
  display: grid; place-items: center;
  font-size: 1.4rem;
  margin-bottom: var(--space-5);
  background: var(--card-color-light, var(--color-primary-light));
  color: var(--card-color, var(--color-primary));
}

.topic-card h3 {
  font-family: var(--font-body);
  font-weight: 700;
  font-size: var(--text-lg);
  margin-bottom: var(--space-2);
}

.topic-card p {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-4);
  line-height: 1.65;
}

.topic-card-meta {
  display: flex;
  gap: var(--space-4);
  font-size: var(--text-xs);
  color: var(--color-text-tertiary);
  font-weight: 500;
}

.topic-card-meta span {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

/* ============================================
   AUDIENCE CARDS (horizontal scroll on mobile)
   ============================================ */
.audience-section {
  padding: var(--space-24) var(--space-6);
  background: var(--color-bg-warm);
}

.audience-grid {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-6);
}

@media (max-width: 1024px) {
  .audience-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
  .audience-grid { grid-template-columns: 1fr; }
}

.audience-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  transition: all var(--duration-normal) var(--ease-smooth);
}

.audience-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-md), 0 0 0 1px var(--color-primary);
  transform: translateY(-2px);
}

.audience-card h3 {
  font-family: var(--font-body);
  font-size: var(--text-lg);
  font-weight: 700;
  margin-bottom: var(--space-2);
}

.audience-card p {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-4);
}

.audience-card .btn-ghost {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-primary);
  padding: 0;
}

/* ============================================
   FEATURES GRID
   ============================================ */
.features-section {
  padding: var(--space-24) var(--space-6);
}

.features-grid {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-8);
}

@media (max-width: 1024px) { .features-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 640px) { .features-grid { grid-template-columns: 1fr; } }

.feature-item {
  padding: var(--space-2);
}

.feature-icon {
  width: 40px; height: 40px;
  border-radius: var(--radius-sm);
  background: var(--color-bg-warm);
  display: grid; place-items: center;
  font-size: 1.2rem;
  margin-bottom: var(--space-4);
}

.feature-item h3 {
  font-family: var(--font-body);
  font-weight: 700;
  font-size: var(--text-base);
  margin-bottom: var(--space-2);
}

.feature-item p {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
}

/* ============================================
   NEWSLETTER
   ============================================ */
.newsletter-section {
  padding: var(--space-24) var(--space-6);
  background: var(--color-text);
  color: white;
  text-align: center;
}

.newsletter-inner {
  max-width: 560px;
  margin: 0 auto;
}

.newsletter-section h2 {
  color: white;
  margin-bottom: var(--space-3);
}

.newsletter-section p {
  color: rgba(255,255,255,0.65);
  margin: 0 auto var(--space-8);
}

.newsletter-form {
  display: flex;
  gap: var(--space-3);
  max-width: 460px;
  margin: 0 auto;
}

.newsletter-input {
  flex: 1;
  padding: var(--space-3) var(--space-5);
  border-radius: var(--radius-full);
  border: 1px solid rgba(255,255,255,0.15);
  background: rgba(255,255,255,0.08);
  color: white;
  font-size: var(--text-sm);
  outline: none;
  transition: all var(--duration-fast) ease;
}

.newsletter-input::placeholder { color: rgba(255,255,255,0.4); }
.newsletter-input:focus {
  border-color: rgba(255,255,255,0.4);
  box-shadow: 0 0 0 3px rgba(255,255,255,0.1);
}

.newsletter-btn {
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-full);
  background: white;
  color: var(--color-text);
  font-weight: 600;
  font-size: var(--text-sm);
  transition: all var(--duration-fast) ease;
  white-space: nowrap;
}

.newsletter-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 20px rgba(255,255,255,0.3);
}

@media (max-width: 480px) {
  .newsletter-form { flex-direction: column; }
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
  padding: var(--space-16) var(--space-6) var(--space-8);
  border-top: 1px solid var(--color-border);
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr repeat(3, 1fr);
  gap: var(--space-12);
  margin-bottom: var(--space-12);
}

@media (max-width: 768px) {
  .footer-grid { grid-template-columns: 1fr 1fr; gap: var(--space-8); }
}
@media (max-width: 480px) {
  .footer-grid { grid-template-columns: 1fr; }
}

.footer-brand p {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  max-width: 300px;
  margin-top: var(--space-3);
}

.footer-col h4 {
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-4);
  color: var(--color-text-tertiary);
}

.footer-col a {
  display: block;
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  padding: var(--space-1) 0;
  transition: color var(--duration-fast) ease;
}

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

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: var(--space-8);
  border-top: 1px solid var(--color-border);
  font-size: var(--text-xs);
  color: var(--color-text-tertiary);
}

/* ============================================
   ARTICLE PAGE STYLES
   ============================================ */
.article-hero {
  padding: calc(var(--nav-height) + var(--space-16)) var(--space-6) var(--space-12);
  max-width: 860px;
  margin: 0 auto;
}

.article-breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-6);
}

.article-breadcrumb a {
  color: var(--color-text-secondary);
  transition: color var(--duration-fast) ease;
}

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

.article-section-badge {
  display: inline-flex;
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-4);
}

.article-meta {
  display: flex;
  gap: var(--space-6);
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
  margin-top: var(--space-6);
}

.article-content {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 var(--space-6) var(--space-24);
}

/* Article typography */
.article-content h2 {
  margin-top: var(--space-16);
  padding-top: var(--space-8);
  border-top: 1px solid var(--color-border-light);
}

.article-content h3 {
  margin-top: var(--space-10);
}

.article-content p {
  margin-bottom: var(--space-5);
}

.article-content a {
  color: var(--color-primary);
  text-decoration: underline;
  text-decoration-color: var(--color-primary-glow);
  text-underline-offset: 3px;
  transition: text-decoration-color var(--duration-fast) ease;
}

.article-content a:hover {
  text-decoration-color: var(--color-primary);
}

.article-content blockquote {
  border-left: 3px solid var(--color-primary);
  padding: var(--space-4) var(--space-6);
  margin: var(--space-8) 0;
  background: var(--color-primary-light);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-style: italic;
  color: var(--color-text-secondary);
}

.article-content pre {
  background: var(--color-text);
  color: #e2e8f0;
  padding: var(--space-6);
  border-radius: var(--radius-md);
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: 1.7;
  margin: var(--space-6) 0;
  position: relative;
}

.article-content code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--color-bg-code);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--color-primary-dark);
}

.article-content pre code {
  background: none;
  padding: 0;
  color: inherit;
}

.article-content table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--space-6) 0;
  font-size: var(--text-sm);
}

.article-content th {
  text-align: left;
  padding: var(--space-3) var(--space-4);
  border-bottom: 2px solid var(--color-border);
  font-weight: 600;
  color: var(--color-text);
}

.article-content td {
  padding: var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--color-border-light);
}

.article-content ul, .article-content ol {
  margin: var(--space-4) 0;
  padding-left: var(--space-6);
}

.article-content li {
  margin-bottom: var(--space-2);
  list-style: disc;
}

.article-content ol li { list-style: decimal; }

/* ============================================
   SEARCH MODAL
   ============================================ */
.search-overlay {
  position: fixed;
  inset: 0;
  z-index: 9999;
  background: rgba(0,0,0,0.5);
  backdrop-filter: blur(4px);
  display: none;
  place-items: start center;
  padding-top: 15vh;
}

.search-overlay.open { display: grid; }

.search-modal {
  width: 90%;
  max-width: 600px;
  background: var(--color-bg-card);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xl);
  overflow: hidden;
  animation: searchIn 250ms var(--ease-out);
}

@keyframes searchIn {
  from { opacity: 0; transform: translateY(-20px) scale(0.98); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

.search-input-wrap {
  display: flex;
  align-items: center;
  padding: var(--space-4) var(--space-6);
  border-bottom: 1px solid var(--color-border);
  gap: var(--space-3);
}

.search-input-wrap svg { color: var(--color-text-tertiary); flex-shrink: 0; }

.search-input {
  flex: 1;
  border: none;
  outline: none;
  font-size: var(--text-lg);
  background: transparent;
  color: var(--color-text);
}

.search-input::placeholder { color: var(--color-text-muted); }

.search-results {
  max-height: 400px;
  overflow-y: auto;
  padding: var(--space-3);
}

.search-result-item {
  display: block;
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-md);
  transition: background var(--duration-fast) ease;
}

.search-result-item:hover { background: var(--color-bg-warm); }

.search-result-item h4 {
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  margin-bottom: 2px;
}

.search-result-item p {
  font-size: var(--text-xs);
  color: var(--color-text-tertiary);
  margin: 0;
}

/* ============================================
   SCROLL REVEAL ANIMATIONS
   ============================================ */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 700ms var(--ease-out), transform 700ms var(--ease-out);
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

.reveal-delay-1 { transition-delay: 100ms; }
.reveal-delay-2 { transition-delay: 200ms; }
.reveal-delay-3 { transition-delay: 300ms; }
.reveal-delay-4 { transition-delay: 400ms; }

/* ============================================
   FADE-IN-UP KEYFRAME
   ============================================ */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes slideDown {
  from { opacity: 0; transform: translateY(-10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ============================================
   PROGRESS BAR (scroll indicator)
   ============================================ */
.scroll-progress {
  position: fixed;
  top: var(--nav-height);
  left: 0; right: 0;
  height: 3px;
  background: var(--color-border-light);
  z-index: 999;
}

.scroll-progress-bar {
  height: 100%;
  background: var(--color-primary);
  width: 0%;
  transition: width 50ms linear;
}

/* ============================================
   BACK TO TOP BUTTON
   ============================================ */
.back-to-top {
  position: fixed;
  bottom: var(--space-8);
  right: var(--space-8);
  width: 44px; height: 44px;
  border-radius: var(--radius-full);
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-md);
  display: grid; place-items: center;
  opacity: 0;
  pointer-events: none;
  transform: translateY(10px);
  transition: all var(--duration-normal) var(--ease-smooth);
  z-index: 100;
}

.back-to-top.visible {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}

.back-to-top:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

/* ============================================
   TABLE OF CONTENTS (Article sidebar)
   ============================================ */
.toc {
  position: sticky;
  top: calc(var(--nav-height) + var(--space-8));
  max-height: calc(100vh - var(--nav-height) - var(--space-16));
  overflow-y: auto;
  padding-right: var(--space-4);
}

.toc h4 {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-4);
}

.toc a {
  display: block;
  padding: var(--space-1) var(--space-3);
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
  border-left: 2px solid transparent;
  transition: all var(--duration-fast) ease;
  line-height: 1.5;
}

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

.toc a.active {
  color: var(--color-primary);
  border-left-color: var(--color-primary);
  font-weight: 500;
}

/* ============================================
   REDUCED MOTION
   ============================================ */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .hero::before { animation: none; }
  .reveal { opacity: 1; transform: none; }
}