/* ========================================
   AutoSmart - Car Buying Guide 2026
   Automotive Showroom Aesthetic
   ======================================== */

/* --- CSS Variables --- */
:root {
  --bg-primary: #1c1c2e;
  --bg-secondary: #22223a;
  --bg-card: #282845;
  --bg-card-hover: #2e2e50;
  --chrome: #c0c0c0;
  --chrome-dark: #8a8a8a;
  --chrome-light: #e0e0e0;
  --racing-red: #cc0000;
  --racing-red-dark: #990000;
  --racing-red-glow: rgba(204, 0, 0, 0.3);
  --text-primary: #f0f0f0;
  --text-secondary: #b0b0c0;
  --text-muted: #707088;
  --border-subtle: rgba(192, 192, 192, 0.12);
  --border-accent: rgba(204, 0, 0, 0.4);
  --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.4);
  --shadow-hover: 0 8px 40px rgba(0, 0, 0, 0.6);
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --radius: 6px;
  --radius-lg: 12px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
  font-size: 16px;
}

body {
  font-family: 'Work Sans', sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* Brushed metal texture overlay */
body::before {
  content: '';
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background:
    repeating-linear-gradient(
      90deg,
      transparent,
      transparent 2px,
      rgba(192, 192, 192, 0.008) 2px,
      rgba(192, 192, 192, 0.008) 3px
    );
  pointer-events: none;
  z-index: 0;
}

/* --- Typography --- */
h1, h2, h3, h4, h5 {
  font-family: 'Fjalla One', sans-serif;
  letter-spacing: 0.02em;
  line-height: 1.2;
  color: var(--text-primary);
}

h1 { font-size: clamp(2.2rem, 5vw, 3.8rem); }
h2 { font-size: clamp(1.6rem, 3vw, 2.4rem); }
h3 { font-size: clamp(1.2rem, 2vw, 1.6rem); }
h4 { font-size: 1.15rem; }

p { color: var(--text-secondary); margin-bottom: 1rem; }
a { color: var(--racing-red); text-decoration: none; transition: var(--transition); }
a:hover { color: #ff3333; }

/* --- Utility --- */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
  position: relative;
  z-index: 1;
}

.section-header {
  text-align: center;
  margin-bottom: 48px;
}

.section-header h2 {
  display: inline-block;
  position: relative;
  padding-bottom: 12px;
}

.section-header h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 3px;
  background: var(--racing-red);
}

.section-header p {
  margin-top: 16px;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

section {
  padding: 80px 0;
  position: relative;
  z-index: 1;
}

/* --- Navigation --- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(28, 28, 46, 0.92);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-subtle);
  transition: var(--transition);
}

.nav-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 70px;
}

.nav-logo {
  font-family: 'Fjalla One', sans-serif;
  font-size: 1.6rem;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.nav-logo .logo-icon {
  width: 32px;
  height: 32px;
  background: var(--racing-red);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
  font-weight: 700;
}

.nav-logo span { color: var(--racing-red); }

.nav-links {
  display: flex;
  gap: 6px;
  list-style: none;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.nav-links a {
  color: var(--text-secondary);
  font-size: 0.82rem;
  font-weight: 500;
  padding: 6px 12px;
  border-radius: var(--radius);
  transition: var(--transition);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  white-space: nowrap;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--text-primary);
  background: rgba(204, 0, 0, 0.15);
}

.nav-hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 8px;
  z-index: 1001;
}

.nav-hamburger span {
  width: 24px;
  height: 2px;
  background: var(--chrome);
  transition: var(--transition);
}

/* --- Hero --- */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  position: relative;
  overflow: hidden;
  padding-top: 70px;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background:
    radial-gradient(ellipse at 20% 50%, rgba(204, 0, 0, 0.08) 0%, transparent 50%),
    radial-gradient(ellipse at 80% 50%, rgba(192, 192, 192, 0.05) 0%, transparent 50%),
    linear-gradient(180deg, var(--bg-primary) 0%, rgba(28, 28, 46, 0.8) 100%);
  z-index: 0;
}

/* Diagonal racing stripes */
.hero::after {
  content: '';
  position: absolute;
  top: -50%; left: -50%;
  width: 200%; height: 200%;
  background: repeating-linear-gradient(
    -45deg,
    transparent,
    transparent 80px,
    rgba(204, 0, 0, 0.02) 80px,
    rgba(204, 0, 0, 0.02) 82px
  );
  z-index: 0;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 900px;
  padding: 0 24px;
}

.hero-badge {
  display: inline-block;
  padding: 6px 20px;
  background: rgba(204, 0, 0, 0.15);
  border: 1px solid var(--border-accent);
  border-radius: 30px;
  color: var(--racing-red);
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 24px;
  animation: fadeSlideDown 0.8s ease forwards;
}

.hero h1 {
  margin-bottom: 20px;
  animation: fadeSlideDown 0.8s ease 0.1s forwards;
  opacity: 0;
}

.hero h1 .accent { color: var(--racing-red); }

.hero-subtitle {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 640px;
  margin: 0 auto 40px;
  animation: fadeSlideDown 0.8s ease 0.2s forwards;
  opacity: 0;
}

/* Key stats */
.hero-stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  margin-bottom: 40px;
  animation: fadeSlideDown 0.8s ease 0.3s forwards;
  opacity: 0;
}

.stat-card {
  background: rgba(40, 40, 69, 0.8);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 24px 16px;
  position: relative;
  overflow: hidden;
}

.stat-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, var(--racing-red), transparent);
}

.stat-value {
  font-family: 'Fjalla One', sans-serif;
  font-size: 1.8rem;
  color: var(--chrome-light);
  margin-bottom: 4px;
}

.stat-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.hero-cta {
  display: flex;
  gap: 16px;
  justify-content: center;
  animation: fadeSlideDown 0.8s ease 0.4s forwards;
  opacity: 0;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  border-radius: var(--radius);
  font-family: 'Fjalla One', sans-serif;
  font-size: 1rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  cursor: pointer;
  border: none;
  transition: var(--transition);
}

.btn-primary {
  background: var(--racing-red);
  color: #fff;
  box-shadow: 0 4px 20px var(--racing-red-glow);
}

.btn-primary:hover {
  background: #dd1111;
  transform: translateY(-2px);
  box-shadow: 0 6px 30px var(--racing-red-glow);
  color: #fff;
}

.btn-outline {
  background: transparent;
  color: var(--chrome);
  border: 1px solid var(--chrome-dark);
}

.btn-outline:hover {
  border-color: var(--chrome);
  color: var(--text-primary);
  transform: translateY(-2px);
}

/* --- Category Navigation Cards --- */
.cat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
  gap: 16px;
  margin-top: 32px;
}

.cat-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 28px 16px;
  text-align: center;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.cat-card:hover {
  background: var(--bg-card-hover);
  border-color: rgba(204, 0, 0, 0.3);
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.cat-card .cat-icon {
  font-size: 2rem;
  margin-bottom: 12px;
  display: block;
}

.cat-card h4 {
  font-size: 0.95rem;
  color: var(--chrome-light);
}

.cat-card p {
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-top: 6px;
  margin-bottom: 0;
}

/* --- Ad Slots --- */
.ad-slot {
  min-height: 250px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px dashed rgba(192, 192, 192, 0.2);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  font-size: 0.85rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin: 40px auto;
  max-width: 1200px;
  border-radius: var(--radius);
}

/* --- Guide Articles --- */
.guides-grid {
  display: grid;
  gap: 32px;
}

.guide-article {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 40px;
  position: relative;
  overflow: hidden;
  transition: var(--transition);
}

.guide-article:hover {
  border-color: rgba(204, 0, 0, 0.25);
}

.guide-article::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 4px;
  height: 100%;
  background: var(--racing-red);
  opacity: 0;
  transition: var(--transition);
}

.guide-article:hover::before { opacity: 1; }

.guide-num {
  font-family: 'Fjalla One', sans-serif;
  font-size: 3rem;
  color: rgba(204, 0, 0, 0.15);
  position: absolute;
  top: 16px;
  right: 24px;
  line-height: 1;
}

.guide-article h3 {
  margin-bottom: 16px;
  color: var(--chrome-light);
  font-size: 1.4rem;
}

.guide-article .guide-content p {
  font-size: 0.95rem;
  line-height: 1.8;
}

.guide-article .guide-content ul,
.guide-article .guide-content ol {
  padding-left: 20px;
  margin: 12px 0;
  color: var(--text-secondary);
}

.guide-article .guide-content li {
  margin-bottom: 6px;
  font-size: 0.93rem;
}

.guide-article .guide-content strong {
  color: var(--chrome-light);
}

.guide-tag {
  display: inline-block;
  padding: 3px 12px;
  background: rgba(204, 0, 0, 0.12);
  border-radius: 20px;
  color: var(--racing-red);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 12px;
}

/* --- Calculators --- */
.calc-section {
  background: var(--bg-secondary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 48px;
  margin-bottom: 40px;
}

.calc-section h3 {
  font-size: 1.5rem;
  margin-bottom: 8px;
  color: var(--chrome-light);
}

.calc-section > p {
  margin-bottom: 32px;
}

.calc-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  align-items: start;
}

.calc-inputs { display: flex; flex-direction: column; gap: 20px; }

.input-group label {
  display: block;
  font-size: 0.82rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 6px;
}

.input-group input,
.input-group select {
  width: 100%;
  padding: 12px 16px;
  background: rgba(28, 28, 46, 0.8);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius);
  color: var(--text-primary);
  font-family: 'Work Sans', sans-serif;
  font-size: 1rem;
  transition: var(--transition);
}

.input-group input:focus,
.input-group select:focus {
  outline: none;
  border-color: var(--racing-red);
  box-shadow: 0 0 0 3px var(--racing-red-glow);
}

.input-group .input-hint {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 4px;
}

.calc-result {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 32px;
  text-align: center;
}

.calc-result-value {
  font-family: 'Fjalla One', sans-serif;
  font-size: 3rem;
  color: var(--racing-red);
  margin: 16px 0 8px;
}

.calc-result-label {
  font-size: 0.85rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.calc-result-breakdown {
  margin-top: 24px;
  border-top: 1px solid var(--border-subtle);
  padding-top: 20px;
}

.calc-result-breakdown .breakdown-row {
  display: flex;
  justify-content: space-between;
  padding: 8px 0;
  font-size: 0.9rem;
}

.breakdown-row .label { color: var(--text-secondary); }
.breakdown-row .value { color: var(--chrome-light); font-weight: 600; }

.calc-btn {
  margin-top: 8px;
}

/* Lease vs buy side-by-side */
.lvb-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
}

.lvb-column {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 28px;
}

.lvb-column h4 {
  text-align: center;
  margin-bottom: 20px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--racing-red);
}

.lvb-column .input-group { margin-bottom: 16px; }

.lvb-result-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-top: 32px;
}

.lvb-result-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 24px;
  text-align: center;
}

.lvb-result-card h5 {
  font-size: 0.9rem;
  color: var(--text-muted);
  text-transform: uppercase;
  margin-bottom: 12px;
}

.lvb-result-card .amount {
  font-family: 'Fjalla One', sans-serif;
  font-size: 2rem;
  color: var(--chrome-light);
}

.lvb-result-card .sub {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-top: 4px;
}

.lvb-result-card.winner {
  border-color: var(--racing-red);
  box-shadow: 0 0 20px var(--racing-red-glow);
}

.lvb-result-card.winner .amount { color: var(--racing-red); }

/* --- Comparison Tables --- */
.comparison-table-wrap {
  overflow-x: auto;
  margin-bottom: 40px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-subtle);
}

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.comparison-table thead {
  background: linear-gradient(135deg, rgba(204, 0, 0, 0.2), rgba(204, 0, 0, 0.08));
}

.comparison-table th {
  padding: 16px 20px;
  text-align: left;
  font-family: 'Fjalla One', sans-serif;
  font-size: 0.9rem;
  color: var(--chrome-light);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  white-space: nowrap;
}

.comparison-table td {
  padding: 14px 20px;
  border-top: 1px solid var(--border-subtle);
  color: var(--text-secondary);
}

.comparison-table tbody tr {
  background: var(--bg-card);
  transition: var(--transition);
}

.comparison-table tbody tr:nth-child(even) {
  background: rgba(40, 40, 69, 0.5);
}

.comparison-table tbody tr:hover {
  background: var(--bg-card-hover);
}

.comparison-table .highlight-cell {
  color: var(--racing-red);
  font-weight: 600;
}

/* --- Interactive Checklist --- */
.checklist-section {
  background: var(--bg-secondary);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-subtle);
  padding: 48px;
}

.checklist-progress {
  margin-bottom: 40px;
}

.progress-bar-outer {
  width: 100%;
  height: 8px;
  background: rgba(192, 192, 192, 0.1);
  border-radius: 4px;
  overflow: hidden;
  margin-top: 12px;
}

.progress-bar-inner {
  height: 100%;
  background: linear-gradient(90deg, var(--racing-red), #ff4444);
  border-radius: 4px;
  transition: width 0.5s ease;
  width: 0%;
}

.progress-text {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 8px;
}

.checklist-phase {
  margin-bottom: 32px;
}

.checklist-phase h4 {
  color: var(--chrome-light);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.phase-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  background: var(--racing-red);
  border-radius: 50%;
  font-family: 'Fjalla One', sans-serif;
  font-size: 0.85rem;
  color: #fff;
}

.checklist-items {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.checklist-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius);
  cursor: pointer;
  transition: var(--transition);
  user-select: none;
}

.checklist-item:hover {
  border-color: rgba(204, 0, 0, 0.3);
}

.checklist-item.checked {
  border-color: rgba(204, 0, 0, 0.3);
  background: rgba(204, 0, 0, 0.05);
}

.checklist-item.checked .check-text {
  text-decoration: line-through;
  color: var(--text-muted);
}

.check-box {
  width: 22px;
  height: 22px;
  border: 2px solid var(--chrome-dark);
  border-radius: 4px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: var(--transition);
}

.checklist-item.checked .check-box {
  background: var(--racing-red);
  border-color: var(--racing-red);
}

.check-box svg {
  width: 14px;
  height: 14px;
  opacity: 0;
  transition: var(--transition);
}

.checklist-item.checked .check-box svg { opacity: 1; }

.check-text {
  font-size: 0.93rem;
  color: var(--text-secondary);
  transition: var(--transition);
}

/* --- Glossary --- */
.glossary-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 16px;
}

.glossary-item {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius);
  padding: 20px;
  transition: var(--transition);
}

.glossary-item:hover {
  border-color: rgba(204, 0, 0, 0.25);
}

.glossary-term {
  font-family: 'Fjalla One', sans-serif;
  font-size: 1rem;
  color: var(--racing-red);
  margin-bottom: 4px;
}

.glossary-def {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 0;
}

/* --- FAQ --- */
.faq-list {
  max-width: 900px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius);
  overflow: hidden;
  transition: var(--transition);
}

.faq-item.open {
  border-color: rgba(204, 0, 0, 0.3);
}

.faq-question {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 24px;
  cursor: pointer;
  font-weight: 600;
  color: var(--chrome-light);
  font-size: 1rem;
  transition: var(--transition);
  gap: 16px;
}

.faq-question:hover { color: var(--text-primary); }

.faq-toggle {
  width: 24px;
  height: 24px;
  flex-shrink: 0;
  transition: transform 0.3s ease;
  color: var(--racing-red);
}

.faq-item.open .faq-toggle { transform: rotate(45deg); }

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, padding 0.3s ease;
}

.faq-item.open .faq-answer {
  max-height: 600px;
}

.faq-answer-inner {
  padding: 0 24px 20px;
  font-size: 0.93rem;
  color: var(--text-secondary);
  line-height: 1.8;
}

/* --- Footer --- */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-subtle);
  padding: 48px 0 32px;
  position: relative;
  z-index: 1;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}

.footer-brand h3 {
  font-size: 1.4rem;
  margin-bottom: 12px;
}

.footer-brand h3 span { color: var(--racing-red); }

.footer-brand p {
  font-size: 0.88rem;
  max-width: 300px;
}

.footer-col h4 {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--chrome);
  margin-bottom: 16px;
}

.footer-col ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.footer-col a {
  font-size: 0.88rem;
  color: var(--text-muted);
  transition: var(--transition);
}

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

.footer-bottom {
  border-top: 1px solid var(--border-subtle);
  padding-top: 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.82rem;
  color: var(--text-muted);
  flex-wrap: wrap;
  gap: 12px;
}

/* --- Disclaimer --- */
.disclaimer {
  background: rgba(204, 0, 0, 0.06);
  border: 1px solid rgba(204, 0, 0, 0.2);
  border-radius: var(--radius);
  padding: 24px;
  margin-top: 20px;
}

.disclaimer h4 {
  color: var(--racing-red);
  margin-bottom: 8px;
  font-size: 0.95rem;
}

.disclaimer p {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 0;
  line-height: 1.6;
}

/* --- Speedometer Progress Indicator --- */
.speedometer {
  width: 160px;
  height: 80px;
  position: relative;
  margin: 0 auto 16px;
}

.speedometer svg {
  width: 100%;
  height: 100%;
}

/* --- Back to top --- */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 48px;
  height: 48px;
  background: var(--racing-red);
  border: none;
  border-radius: 50%;
  color: #fff;
  font-size: 1.2rem;
  cursor: pointer;
  opacity: 0;
  transform: translateY(20px);
  transition: var(--transition);
  z-index: 999;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 20px var(--racing-red-glow);
}

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

.back-to-top:hover {
  background: #dd1111;
  transform: translateY(-3px);
}

/* --- Animations --- */
@keyframes fadeSlideDown {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* --- Responsive --- */
@media (max-width: 1024px) {
  .hero-stats { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .calc-grid { grid-template-columns: 1fr; }
  .lvb-grid { grid-template-columns: 1fr; }
  .lvb-result-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
  section { padding: 60px 0; }

  .nav-links { display: none; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 70px;
    left: 0;
    right: 0;
    background: rgba(28, 28, 46, 0.98);
    padding: 16px 24px;
    border-bottom: 1px solid var(--border-subtle);
    gap: 4px;
  }

  .nav-links.open a {
    padding: 12px 16px;
    font-size: 0.9rem;
  }

  .nav-hamburger { display: flex; }

  .hero-stats { grid-template-columns: 1fr 1fr; gap: 12px; }
  .stat-value { font-size: 1.4rem; }
  .stat-card { padding: 16px 12px; }

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

  .guide-article { padding: 28px 20px; }
  .guide-num { font-size: 2rem; top: 12px; right: 16px; }

  .calc-section { padding: 28px 20px; }
  .calc-result-value { font-size: 2rem; }

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

  .footer-grid { grid-template-columns: 1fr; gap: 32px; }

  .checklist-section { padding: 28px 20px; }

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

@media (max-width: 480px) {
  .hero-stats { grid-template-columns: 1fr; }
  .lvb-result-grid { grid-template-columns: 1fr; }
  .cat-grid { grid-template-columns: 1fr; }
}

/* --- Scrollbar --- */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: var(--bg-primary); }
::-webkit-scrollbar-thumb { background: var(--chrome-dark); border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: var(--chrome); }

/* --- Selection --- */
::selection {
  background: rgba(204, 0, 0, 0.4);
  color: #fff;
}