:root {
  --color-white: #ffffff;
  --color-light: #f5f5f7;
  --color-border: #e5e5ea;
  --color-muted: #86868b;
  --color-text: #1d1d1f;
  --color-black: #000000;

  --font-system: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Inter", "Segoe UI", sans-serif;

  --container: 1120px;
  --article: 760px;
  --radius-sm: 16px;
  --radius-md: 22px;
  --radius-lg: 32px;

  --space-xs: 0.5rem;
  --space-sm: 0.875rem;
  --space-md: 1.5rem;
  --space-lg: 2.5rem;
  --space-xl: 4rem;
  --space-2xl: 6rem;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-system);
  color: var(--color-text);
  background: var(--color-white);
  line-height: 1.5;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

img,
svg,
video {
  max-width: 100%;
  height: auto;
}

button,
input {
  font: inherit;
}

.container {
  width: min(100% - 2rem, var(--container));
  margin-inline: auto;
}

.skip-link {
  position: absolute;
  left: -999px;
  top: 1rem;
  z-index: 100;
  background: var(--color-black);
  color: var(--color-white);
  padding: 0.75rem 1rem;
  border-radius: 999px;
}

.skip-link:focus {
  left: 1rem;
}

.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;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, 0.88);
  border-bottom: 1px solid var(--color-border);
  backdrop-filter: blur(16px);
}

.header-inner {
  min-height: 70px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  font-weight: 700;
  letter-spacing: -0.03em;
}

.brand-mark {
  width: 38px;
  height: 38px;
  display: inline-grid;
  place-items: center;
  border-radius: 50%;
  background: var(--color-text);
  color: var(--color-white);
  font-size: 0.74rem;
  letter-spacing: -0.02em;
}

.brand-name {
  font-size: 1.05rem;
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 1.4rem;
  color: var(--color-muted);
  font-size: 0.95rem;
  font-weight: 500;
}

.main-nav a:hover,
.header-search:hover,
.footer-inner a:hover {
  color: var(--color-black);
}

.header-search {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 40px;
  padding: 0 1.05rem;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  color: var(--color-text);
  font-size: 0.94rem;
  font-weight: 600;
}

.section {
  padding: clamp(5rem, 8vw, 8rem) 0;
}

.section-muted {
  background: var(--color-light);
}

.hero {
  padding-top: 5rem;
  padding-bottom: 5.5rem;
}

.hero-inner {
  max-width: 860px;
  text-align: center;
}

.eyebrow {
  margin: 0 0 1rem;
  color: var(--color-muted);
  font-size: 0.88rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 1.2rem;
  font-size: clamp(3.3rem, 7.6vw, 6.4rem);
  line-height: 0.96;
  letter-spacing: -0.018em;
  font-weight: 650;
}

h2 {
  margin-bottom: 0.85rem;
  font-size: clamp(2.2rem, 4.8vw, 4.2rem);
  line-height: 1.03;
  letter-spacing: -0.015em;
  font-weight: 650;
}

h3 {
  margin-bottom: 0.7rem;
  font-size: 1.35rem;
  line-height: 1.18;
  letter-spacing: -0.008em;
  font-weight: 650;
}

.hero-subtitle {
  max-width: 720px;
  margin: 0 auto 2rem;
  color: var(--color-muted);
  font-size: clamp(1.15rem, 2vw, 1.45rem);
  line-height: 1.38;
  letter-spacing: -0.03em;
}

.search-panel {
  display: flex;
  gap: 0.65rem;
  max-width: 680px;
  margin: 0 auto;
  padding: 0.55rem;
  background: var(--color-light);
  border: 1px solid var(--color-border);
  border-radius: 999px;
}

.search-panel input {
  min-width: 0;
  flex: 1;
  border: 0;
  outline: 0;
  background: transparent;
  color: var(--color-text);
  padding: 0.95rem 1.1rem;
  font-size: 1rem;
}

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

.search-panel button,
.button-primary {
  border: 0;
  border-radius: 999px;
  background: var(--color-text);
  color: var(--color-white);
  padding: 0.95rem 1.45rem;
  font-weight: 700;
  cursor: pointer;
}

.search-panel button:hover,
.button-primary:hover {
  background: var(--color-black);
}

.popular-searches {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.75rem 1rem;
  margin-top: 1.25rem;
  color: var(--color-muted);
  font-size: 0.95rem;
}

.popular-searches a {
  color: var(--color-text);
  font-weight: 600;
}

.section-heading {
  max-width: 760px;
  margin-bottom: var(--space-lg);
}

.section-heading p,
.body-large,
.cta-panel p {
  color: var(--color-muted);
  font-size: 1.15rem;
  line-height: 1.55;
  letter-spacing: -0.02em;
}

.topic-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.topic-card,
.video-card,
.cta-panel,
.question-list a {
  background: var(--color-white);
  border: 1px solid var(--color-border);
}

.topic-card {
  min-height: 250px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 1.5rem;
  border-radius: var(--radius-lg);
  transition: transform 160ms ease, border-color 160ms ease;
}

.topic-card:hover {
  transform: translateY(-2px);
  border-color: #c9c9cf;
}

.topic-card p {
  color: var(--color-muted);
  font-size: 1rem;
}

.topic-card span,
.video-content a {
  color: var(--color-black);
  font-weight: 700;
}

.split-layout {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: var(--space-xl);
  align-items: start;
}

.question-list {
  display: grid;
  gap: 0.8rem;
}

.question-list a {
  display: block;
  padding: 1.2rem 1.3rem;
  border-radius: var(--radius-md);
  font-size: 1.08rem;
  font-weight: 700;
  letter-spacing: -0.03em;
}

.question-list a:hover {
  border-color: #c9c9cf;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.video-card {
  overflow: hidden;
  border-radius: var(--radius-lg);
}

.video-thumb {
  aspect-ratio: 16 / 9;
}

.placeholder-thumb {
  display: grid;
  place-items: center;
  background: linear-gradient(135deg, #202124, #6e6e73);
  color: var(--color-white);
  font-weight: 800;
  letter-spacing: -0.04em;
}

.video-content {
  padding: 1.3rem;
}

.video-content p {
  color: var(--color-muted);
}

.cta-panel {
  max-width: 900px;
  margin-inline: auto;
  padding: clamp(2rem, 5vw, 4rem);
  text-align: center;
  border-radius: var(--radius-lg);
  background: var(--color-white);
}

.button-primary {
  display: inline-flex;
  margin-top: 1rem;
}

.site-footer {
  padding: 2.5rem 0;
  border-top: 1px solid var(--color-border);
  color: var(--color-muted);
  background: var(--color-light);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  font-size: 0.94rem;
}

.footer-inner p {
  margin: 0;
}

.footer-inner nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 1rem;
}

@media (max-width: 860px) {
  .header-inner {
    min-height: auto;
    padding: 1rem 0;
    flex-wrap: wrap;
  }

  .main-nav {
    order: 3;
    width: 100%;
    justify-content: center;
    gap: 1rem;
  }

  .brand-name {
    font-size: 1rem;
  }

  .hero {
    padding-top: 4rem;
  }

  .topic-grid,
  .video-grid,
  .split-layout {
    grid-template-columns: 1fr;
  }

  .topic-card {
    min-height: 210px;
  }

  .footer-inner {
    flex-direction: column;
    text-align: center;
  }

  .footer-inner nav {
    justify-content: center;
  }
}

@media (max-width: 560px) {
  .container {
    width: min(100% - 1.25rem, var(--container));
  }

  .section {
    padding: 4rem 0;
  }

  .hero {
    padding-top: 3.5rem;
  }

  .search-panel {
    flex-direction: column;
    border-radius: var(--radius-md);
  }

  .search-panel button {
    width: 100%;
  }

  .main-nav {
    overflow-x: auto;
    justify-content: flex-start;
    padding-bottom: 0.25rem;
  }

  .header-search {
    min-height: 36px;
    padding: 0 0.9rem;
  }
}

/* Pillar page template */
.page-hero {
  padding: clamp(4.5rem, 8vw, 8rem) 0 clamp(3.5rem, 6vw, 6rem);
  background: var(--color-white);
}

.page-hero-inner {
  max-width: 860px;
}

.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  margin-bottom: 1.25rem;
  color: var(--color-muted);
  font-size: 0.95rem;
}

.breadcrumbs a {
  color: var(--color-text);
  font-weight: 600;
}

.page-intro {
  max-width: 760px;
  color: var(--color-muted);
  font-size: clamp(1.15rem, 2vw, 1.45rem);
  line-height: 1.45;
  letter-spacing: -0.02em;
}

.pillar-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 290px;
  gap: clamp(2rem, 5vw, 4rem);
  align-items: start;
}

.article-content {
  max-width: var(--article);
}

.article-content h2 {
  margin-top: 3rem;
  font-size: clamp(2rem, 4vw, 3.4rem);
}

.article-content h3 {
  margin-top: 2rem;
}

.article-content p,
.article-content li {
  color: #424245;
  font-size: 1.08rem;
  line-height: 1.72;
  letter-spacing: -0.01em;
}

.article-content ul {
  padding-left: 1.25rem;
}

.summary-card,
.study-card,
.toc-card,
.related-card {
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
}

.summary-card {
  padding: clamp(1.5rem, 4vw, 2rem);
  margin-bottom: 2rem;
}

.summary-card p:last-child {
  margin-bottom: 0;
}

.toc-card {
  position: sticky;
  top: 95px;
  padding: 1.25rem;
}

.toc-card h2 {
  margin-bottom: 1rem;
  font-size: 1rem;
  line-height: 1.2;
  letter-spacing: -0.01em;
}

.toc-card nav {
  display: grid;
  gap: 0.75rem;
}

.toc-card a {
  color: var(--color-muted);
  font-size: 0.95rem;
  font-weight: 600;
}

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

.study-card {
  padding: clamp(1.5rem, 4vw, 2rem);
  margin-top: 2.5rem;
  background: var(--color-light);
}

.faq-list {
  display: grid;
  gap: 1rem;
}

.faq-item {
  padding: 1.35rem;
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}

.faq-item h3 {
  margin-top: 0;
  font-size: 1.15rem;
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.related-card {
  padding: 1.35rem;
}

.related-card p {
  color: var(--color-muted);
}

@media (max-width: 900px) {
  .pillar-layout {
    grid-template-columns: 1fr;
  }

  .toc-card {
    position: static;
  }

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


.status-pill {
  display: inline-flex;
  align-items: center;
  width: fit-content;
  margin-bottom: 0.85rem;
  padding: 0.36rem 0.72rem;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  color: var(--color-muted);
  background: var(--color-light);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

/* Comparison table */
.comparison-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 1rem;
}

.comparison-table th,
.comparison-table td {
  padding: 0.95rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
}

.comparison-table th {
  color: var(--color-text);
  font-weight: 700;
}

.comparison-table td {
  color: #424245;
}

.comparison-table tr:last-child td {
  border-bottom: 0;
}

/* Anchor scroll offset for sticky header */
html {
  scroll-padding-top: 60px;
}

.article-content h2,
.article-content h3 {
  scroll-margin-top: 60px;
}