/* Acquire HVAC — Page-Specific Styles */

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

/* ══════════════════════════════════════════
   HOMEPAGE
   ══════════════════════════════════════════ */

/* Hero */
.hero {
  padding-top: calc(72px + var(--space-3xl));
  padding-bottom: var(--space-2xl);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: var(--space-2xl);
  align-items: center;
}

.hero-content {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.hero-sub {
  font-size: var(--text-lg);
  color: var(--color-text-muted);
  max-width: 540px;
}

.hero-buttons {
  display: flex;
  gap: var(--space-md);
  margin-top: var(--space-sm);
  flex-wrap: wrap;
}

.hero-image img {
  width: 100%;
  height: auto;
  object-fit: cover;
  aspect-ratio: 4 / 3;
}

/* Hero entrance animation */
.hero-anim {
  opacity: 0;
  transform: translateY(16px);
  animation: heroFadeUp 600ms var(--ease-out) forwards;
  animation-delay: var(--delay, 0ms);
}

.hero-anim-image {
  opacity: 0;
  transform: scale(0.95);
  animation: heroScaleIn 800ms var(--ease-out) 200ms forwards;
}

@keyframes heroFadeUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes heroScaleIn {
  to {
    opacity: 1;
    transform: scale(1);
  }
}

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

  .hero-image {
    order: -1;
  }
}

/* Section headers */
.section-header {
  text-align: center;
  margin-bottom: var(--space-2xl);
}

.section-header .overline {
  margin-bottom: var(--space-sm);
}

.section-header h2 {
  margin-top: var(--space-sm);
}

/* Audience selector */
.audience-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-xl);
}

.audience-card {
  display: flex;
  flex-direction: column;
  background: white;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: transform var(--duration-base) var(--ease-out), box-shadow var(--duration-base) var(--ease-out), border-color var(--duration-base) var(--ease-out);
  border-left: 4px solid transparent;
}

.audience-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  border-left-color: var(--color-accent);
}

.audience-card-img {
  overflow: hidden;
}

.audience-card-img img {
  width: 100%;
  height: 200px;
  object-fit: cover;
  transition: transform var(--duration-base) var(--ease-out);
}

.audience-card:hover .audience-card-img img {
  transform: scale(1.03);
}

.audience-card-body {
  padding: var(--space-lg);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.audience-icon {
  color: var(--color-primary);
}

.audience-card h3 {
  font-size: var(--text-xl);
}

.audience-card p {
  color: var(--color-text-muted);
  font-size: var(--text-sm);
}

.card-link {
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  color: var(--color-accent);
  margin-top: auto;
}

.card-link span {
  display: inline-block;
  transition: transform var(--duration-fast) var(--ease-out);
}

.audience-card:hover .card-link span {
  transform: translateX(4px);
}

@media (max-width: 768px) {
  .audience-grid {
    grid-template-columns: 1fr;
  }
}

/* Chapter overview timeline */
.chapter-timeline {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.chapter-row {
  display: grid;
  grid-template-columns: 60px 120px 1fr auto;
  gap: var(--space-lg);
  align-items: center;
  padding: var(--space-lg);
  border-radius: var(--radius-md);
  transition: background-color var(--duration-fast);
}

.chapter-row:hover {
  background-color: var(--color-surface);
}

.chapter-num {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: var(--weight-extrabold);
  color: var(--color-primary);
}

.chapter-row-img {
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.chapter-row-img img {
  width: 120px;
  height: 80px;
  object-fit: cover;
  border-radius: var(--radius-sm);
}

.chapter-row-content h3 {
  font-size: var(--text-lg);
  margin-bottom: var(--space-xs);
}

.chapter-row-content h3 a {
  color: var(--color-text);
  transition: color var(--duration-fast);
}

.chapter-row-content h3 a:hover {
  color: var(--color-primary);
}

.chapter-row-content p {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin-bottom: 0;
}

.chapter-row-link {
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  color: var(--color-accent);
  white-space: nowrap;
}

.chapter-row-link span {
  display: inline-block;
  transition: transform var(--duration-fast) var(--ease-out);
}

.chapter-row:hover .chapter-row-link span {
  transform: translateX(4px);
}

@media (max-width: 768px) {
  .chapter-row {
    grid-template-columns: 48px 1fr;
    gap: var(--space-md);
  }

  .chapter-row-img {
    display: none;
  }

  .chapter-row-link {
    grid-column: 1 / -1;
  }
}

/* Stats bar */
.stats-bar {
  background-color: var(--color-primary);
  padding: var(--space-2xl) 0;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-xl);
  text-align: center;
}

.stat-number {
  font-family: var(--font-display);
  font-size: var(--text-4xl);
  font-weight: var(--weight-extrabold);
  color: var(--color-accent);
  display: block;
  line-height: var(--leading-tight);
}

.stat-label {
  font-size: var(--text-sm);
  color: var(--color-text-inverse);
  opacity: 0.85;
  display: block;
  margin-top: var(--space-sm);
}

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

  .stat-number {
    font-size: var(--text-2xl);
  }
}

/* Features grid */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.feature-card {
  background: white;
  border-radius: var(--radius-md);
  padding: var(--space-xl);
  box-shadow: var(--shadow-sm);
  transition: transform var(--duration-base) var(--ease-out), box-shadow var(--duration-base) var(--ease-out);
}

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

.feature-icon {
  color: var(--color-primary);
  margin-bottom: var(--space-md);
}

.feature-card h3 {
  font-size: var(--text-lg);
  margin-bottom: var(--space-sm);
}

.feature-card p {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin-bottom: 0;
}

@media (max-width: 768px) {
  .features-grid {
    grid-template-columns: 1fr;
  }
}

/* CTA section */
.cta-section {
  position: relative;
  padding: var(--space-4xl) 0;
  overflow: hidden;
}

.cta-bg {
  position: absolute;
  inset: 0;
}

.cta-bg img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.cta-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(to top, rgba(26, 35, 50, 0.75), rgba(26, 35, 50, 0.55));
}

.cta-content {
  position: relative;
  text-align: center;
  color: var(--color-text-inverse);
  max-width: 640px;
  margin: 0 auto;
}

.cta-content h2 {
  color: var(--color-text-inverse);
  margin-bottom: var(--space-md);
}

.cta-content p {
  opacity: 0.9;
  margin-bottom: var(--space-xl);
}

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

/* ══════════════════════════════════════════
   FOOTER
   ══════════════════════════════════════════ */

.site-footer {
  background-color: var(--color-primary);
  color: var(--color-text-inverse);
  padding: var(--space-3xl) 0 var(--space-xl);
}

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

.footer-col h4 {
  font-family: var(--font-display);
  font-weight: var(--weight-semibold);
  color: var(--color-text-inverse);
  margin-bottom: var(--space-lg);
  font-size: var(--text-base);
}

.footer-col ul {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.footer-col a {
  font-size: var(--text-sm);
  opacity: 0.8;
  transition: opacity var(--duration-fast);
}

.footer-col a:hover {
  opacity: 1;
}

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.15);
  padding-top: var(--space-lg);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-md);
}

.footer-bottom p {
  font-size: var(--text-sm);
  opacity: 0.7;
  margin-bottom: 0;
}

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

  .footer-bottom {
    flex-direction: column;
  }
}

/* ══════════════════════════════════════════
   CHAPTERS HUB PAGE
   ══════════════════════════════════════════ */

.page-header {
  text-align: center;
  padding-top: calc(72px + var(--space-3xl));
  padding-bottom: var(--space-xl);
}

.page-header .overline {
  margin-bottom: var(--space-sm);
}

.page-header h1 {
  margin-bottom: var(--space-md);
}

.page-header .subtitle {
  font-size: var(--text-lg);
  color: var(--color-text-muted);
  max-width: 640px;
  margin: 0 auto;
}

/* Chapter hub cards */
.chapter-cards {
  display: flex;
  flex-direction: column;
  gap: var(--space-xl);
  padding-bottom: var(--space-3xl);
}

.chapter-card {
  display: grid;
  grid-template-columns: 1fr 1fr;
  background: white;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: box-shadow var(--duration-base) var(--ease-out);
  text-decoration: none;
  color: inherit;
}

.chapter-card:hover {
  box-shadow: var(--shadow-lg);
}

.chapter-card-content {
  padding: var(--space-xl);
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: var(--space-md);
  position: relative;
}

.chapter-card-number {
  font-family: var(--font-display);
  font-size: 6rem;
  font-weight: var(--weight-extrabold);
  color: var(--color-primary);
  opacity: 0.12;
  position: absolute;
  top: var(--space-md);
  right: var(--space-xl);
  line-height: 1;
}

.chapter-card h2 {
  position: relative;
  z-index: 1;
}

.chapter-card p {
  color: var(--color-text-muted);
  font-size: var(--text-sm);
  position: relative;
  z-index: 1;
}

.chapter-card-pills {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  position: relative;
  z-index: 1;
}

.chapter-card-link {
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  color: var(--color-accent);
  position: relative;
  z-index: 1;
}

.chapter-card-link span {
  display: inline-block;
  transition: transform var(--duration-fast) var(--ease-out);
}

.chapter-card:hover .chapter-card-link span {
  transform: translateX(4px);
}

.chapter-card-image {
  overflow: hidden;
}

.chapter-card-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--duration-base) var(--ease-out);
}

.chapter-card:hover .chapter-card-image img {
  transform: scale(1.02);
}

@media (max-width: 768px) {
  .chapter-card {
    grid-template-columns: 1fr;
  }

  .chapter-card-image {
    height: 200px;
    order: -1;
  }
}

/* ══════════════════════════════════════════
   INDIVIDUAL CHAPTER PAGES
   ══════════════════════════════════════════ */

/* Chapter hero */
.chapter-hero {
  position: relative;
  padding: 0;
  min-height: 400px;
  display: flex;
  align-items: flex-end;
  background-size: cover;
  background-position: center;
}

.chapter-hero-bg {
  position: absolute;
  inset: 0;
}

.chapter-hero-bg img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.chapter-hero-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(to top, rgba(26, 35, 50, 0.7) 0%, rgba(26, 35, 50, 0.25) 100%);
}

.chapter-hero-content {
  position: relative;
  padding: var(--space-3xl) 0 var(--space-2xl);
  padding-top: calc(72px + var(--space-3xl));
  color: var(--color-text-inverse);
  width: 100%;
}

.chapter-hero-content .overline {
  color: var(--color-accent);
}

.chapter-hero-content h1 {
  color: var(--color-text-inverse);
  margin: var(--space-md) 0;
  max-width: 700px;
}

.chapter-meta {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  flex-wrap: wrap;
}

.chapter-meta .read-time {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: var(--text-sm);
  opacity: 0.85;
}

.chapter-meta .pill {
  background: rgba(255,255,255,0.2);
  color: white;
}

/* Chapter layout — sidebar + content */
.chapter-layout {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: var(--space-2xl);
  padding: var(--space-2xl) 0 var(--space-3xl);
  align-items: start;
}

/* Sticky TOC sidebar */
.chapter-toc {
  position: sticky;
  top: calc(72px + var(--space-lg));
}

.chapter-toc h4 {
  font-size: var(--text-sm);
  text-transform: uppercase;
  letter-spacing: var(--tracking-wide);
  color: var(--color-text-muted);
  margin-bottom: var(--space-md);
}

.chapter-toc ul {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.chapter-toc a {
  display: block;
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  padding: var(--space-xs) var(--space-md);
  border-left: 2px solid var(--color-border);
  transition: color var(--duration-fast), border-color var(--duration-fast), font-weight var(--duration-fast);
}

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

.chapter-toc a.active {
  color: var(--color-text);
  border-left-color: var(--color-accent);
  font-weight: var(--weight-medium);
}

/* Mobile TOC toggle */
.toc-mobile-toggle {
  display: none;
  width: 100%;
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  color: var(--color-text);
  padding: var(--space-md);
  background: var(--color-surface);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-lg);
  justify-content: space-between;
  align-items: center;
}

.toc-mobile-toggle svg {
  width: 20px;
  height: 20px;
  transition: transform var(--duration-fast);
}

.toc-mobile-toggle.open svg {
  transform: rotate(180deg);
}

/* Chapter body content */
.chapter-body {
  max-width: 720px;
}

.chapter-body h2 {
  margin-top: var(--space-2xl);
  margin-bottom: var(--space-lg);
  padding-top: var(--space-lg);
}

.chapter-body h3 {
  margin-top: var(--space-xl);
  margin-bottom: var(--space-md);
}

.chapter-body ul, .chapter-body ol {
  margin: var(--space-md) 0;
  padding-left: var(--space-lg);
}

.chapter-body ul {
  list-style: disc;
}

.chapter-body ol {
  list-style: decimal;
}

.chapter-body li {
  margin-bottom: var(--space-sm);
  font-size: var(--text-base);
}

.chapter-body img {
  border-radius: var(--radius-lg);
  margin: var(--space-xl) 0;
  box-shadow: var(--shadow-md);
}

/* Chapter nav */
.chapter-nav {
  display: flex;
  justify-content: space-between;
  gap: var(--space-lg);
  padding: var(--space-xl) 0;
  border-top: 1px solid var(--color-border);
  margin-top: var(--space-2xl);
}

.chapter-nav a {
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  color: var(--color-text);
  padding: var(--space-md) var(--space-lg);
  border-radius: var(--radius-md);
  transition: background-color var(--duration-fast), color var(--duration-fast);
}

.chapter-nav a:hover {
  background-color: var(--color-surface);
}

.chapter-nav a span {
  display: inline-block;
  transition: transform var(--duration-fast) var(--ease-out);
}

.chapter-nav a:hover .arrow-left {
  transform: translateX(-4px);
}

.chapter-nav a:hover .arrow-right {
  transform: translateX(4px);
}

/* Related topics */
.related-topics {
  padding: var(--space-2xl) 0;
}

.related-topics h3 {
  margin-bottom: var(--space-lg);
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.related-card {
  background: white;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: transform var(--duration-base) var(--ease-out), box-shadow var(--duration-base) var(--ease-out);
  text-decoration: none;
  color: inherit;
}

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

.related-card-img {
  height: 120px;
  overflow: hidden;
}

.related-card-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.related-card-body {
  padding: var(--space-md);
}

.related-card-body .overline {
  font-size: 0.65rem;
  margin-bottom: var(--space-xs);
}

.related-card-body h4 {
  font-size: var(--text-sm);
  margin-bottom: 0;
}

@media (max-width: 768px) {
  .chapter-layout {
    grid-template-columns: 1fr;
  }

  .chapter-toc {
    position: static;
    display: none;
  }

  .chapter-toc.mobile-open {
    display: block;
  }

  .toc-mobile-toggle {
    display: flex;
  }

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

  .chapter-nav {
    flex-direction: column;
  }
}

/* ══════════════════════════════════════════
   ABOUT PAGE
   ══════════════════════════════════════════ */

.about-hero {
  position: relative;
  padding: calc(72px + var(--space-3xl)) 0 var(--space-3xl);
  overflow: hidden;
}

.about-hero-bg {
  position: absolute;
  inset: 0;
}

.about-hero-bg img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.about-hero-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(to bottom, rgba(250, 251, 252, 0.92), rgba(250, 251, 252, 0.97));
}

.about-hero-content {
  position: relative;
  text-align: center;
  max-width: 720px;
  margin: 0 auto;
}

.about-hero-content h1 {
  margin-bottom: var(--space-lg);
}

.about-hero-content p {
  font-size: var(--text-lg);
  color: var(--color-text-muted);
}

/* About features */
.about-features {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.about-feature-card {
  background: white;
  border-radius: var(--radius-md);
  padding: var(--space-xl);
  box-shadow: var(--shadow-sm);
  text-align: center;
  transition: transform var(--duration-base) var(--ease-out), box-shadow var(--duration-base) var(--ease-out);
}

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

.about-feature-card .feature-icon {
  display: flex;
  justify-content: center;
}

.about-feature-card h3 {
  margin-bottom: var(--space-sm);
}

.about-feature-card p {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin-bottom: 0;
}

@media (max-width: 768px) {
  .about-features {
    grid-template-columns: 1fr;
  }
}

/* Editorial standards section */
.editorial-section {
  max-width: 720px;
  margin: 0 auto;
}

.editorial-section img {
  border-radius: var(--radius-lg);
  margin: var(--space-xl) 0;
  box-shadow: var(--shadow-md);
}

/* About CTA */
.about-cta {
  background-color: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
  text-align: center;
  max-width: 640px;
  margin: 0 auto;
}

.about-cta h2 {
  margin-bottom: var(--space-md);
}

.about-cta p {
  color: var(--color-text-muted);
  margin-bottom: var(--space-lg);
}