:root {
  --color-bg: #f4f4f4;
  --color-surface: #ffffff;
  --color-ink: #171717;
  --color-muted: #5e5e5e;
  --color-primary: #171717;
  --color-primary-strong: #000000;
  --color-line: #d9d9d9;
  --color-tint: #e6e6e6;
  --color-ad-bg: #e2e2e2;

  --font-head: Georgia, "Times New Roman", serif;
  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;

  --radius: 12px;
  --max-width: 1100px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  font-family: var(--font-body);
  font-size: 1.0625rem;
  line-height: 1.65;
  color: var(--color-ink);
  background: var(--color-bg);
}

main {
  flex: 1;
}

h1,
h2,
h3,
h4 {
  font-family: var(--font-head);
  line-height: 1.25;
  margin: 0 0 0.5em;
}

h1 {
  font-size: clamp(1.9rem, 1.4rem + 2.2vw, 2.8rem);
}

h2 {
  font-size: clamp(1.35rem, 1.15rem + 0.9vw, 1.8rem);
  margin-top: 2em;
}

h2:first-child {
  margin-top: 0;
}

h3 {
  font-size: 1.15rem;
  margin-top: 1.5em;
}

p {
  margin: 0 0 1em;
}

a {
  color: var(--color-primary);
}

a:hover {
  color: var(--color-primary-strong);
}

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

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 100;
  background: var(--color-ink);
  color: #ffffff;
  padding: 0.7rem 1.2rem;
  border-radius: 0 0 8px 0;
}

.skip-link:focus {
  left: 0;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-line);
}

.site-header__inner {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.4rem 1.25rem;
  padding-top: 0.75rem;
  padding-bottom: 0.75rem;
}

.site-logo {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-head);
  font-size: 1.35rem;
  font-weight: 700;
  line-height: 1.1;
  color: var(--color-ink);
  text-decoration: none;
}

.site-logo:hover {
  color: var(--color-primary-strong);
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.2rem 1.1rem;
  font-size: 0.95rem;
}

.site-nav__link {
  color: var(--color-muted);
  text-decoration: none;
  padding: 0.35rem 0.1rem;
  border-bottom: 2px solid transparent;
}

.site-nav__link:hover {
  color: var(--color-primary);
}

.site-nav__link[aria-current="page"] {
  color: var(--color-ink);
  font-weight: 600;
  border-bottom-color: var(--color-primary);
}

.hero {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-line);
  padding: clamp(3rem, 7vw, 5.5rem) 0;
}

.hero__inner {
  max-width: 42rem;
}

.hero__kicker {
  margin: 0 0 1rem;
  color: var(--color-primary-strong);
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
}

.hero p {
  font-size: 1.15rem;
  color: var(--color-muted);
  max-width: 40rem;
}

.btn {
  display: inline-block;
  margin-top: 0.75rem;
  background: var(--color-primary);
  color: #ffffff;
  padding: 0.75rem 1.4rem;
  border-radius: 8px;
  text-decoration: none;
  font-weight: 600;
}

.btn:hover {
  background: var(--color-primary-strong);
  color: #ffffff;
}

.ad-slot {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 90px;
  border: 2px dashed var(--color-line);
  background: var(--color-ad-bg);
  color: var(--color-muted);
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  text-align: center;
}

.ad-slot--home {
  margin: 2.5rem 0;
}

.ad-slot--sidebar {
  min-height: 250px;
  margin: 0 0 2rem;
}

.section {
  padding: 3.5rem 0;
}

.section__intro {
  color: var(--color-muted);
  max-width: 44rem;
}

.pillar-grid {
  display: grid;
  gap: 1.25rem;
  margin-top: 1.5rem;
}

.pillar-card {
  display: flex;
  flex-direction: column;
  background: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  padding: 1.5rem;
}

.pillar-card h3 {
  margin: 0 0 0.5rem;
}

.pillar-card h3 a {
  color: var(--color-ink);
  text-underline-offset: 4px;
}

.pillar-card h3 a:hover {
  color: var(--color-primary-strong);
}

.pillar-card__desc {
  color: var(--color-muted);
}

.pillar-card__link {
  margin-top: auto;
  padding-top: 0.75rem;
  font-weight: 600;
}

.page {
  padding: 1.5rem 0 4rem;
}

.page-head h1 {
  margin-bottom: 0.4em;
}

.page-head p {
  color: var(--color-muted);
  font-size: 1.1rem;
  max-width: 40rem;
}

.page-intro {
  max-width: 40rem;
}

.breadcrumb {
  margin: 0 0 1.75rem;
  font-size: 0.9rem;
}

.breadcrumb ol {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.breadcrumb li + li::before {
  content: "";
  margin-right: 0.4rem;
  color: var(--color-muted);
}

.breadcrumb a {
  color: var(--color-muted);
}

.lesson-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1.25rem;
}

.lesson-card {
  display: flex;
  flex-direction: column;
  background: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  padding: 1.4rem 1.5rem;
}

.lesson-card h3 {
  margin-bottom: 0.35rem;
}

.lesson-card h3 a {
  color: var(--color-ink);
  text-underline-offset: 4px;
}

.lesson-card h3 a:hover {
  color: var(--color-primary-strong);
}

.lesson-card__desc {
  color: var(--color-muted);
  margin-bottom: 1rem;
}

.tag-list {
  list-style: none;
  margin: 0 0 1rem;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.tag {
  display: inline-block;
  padding: 0.22rem 0.7rem;
  border: 1px solid var(--color-line);
  border-radius: 999px;
  background: var(--color-tint);
  color: var(--color-muted);
  font-size: 0.8rem;
}

.tag-list--head {
  margin-bottom: 1.25rem;
}

.lesson {
  padding: 1.5rem 0 4rem;
}

.lesson__head h1 {
  margin-bottom: 0.3em;
}

.lesson__meta {
  color: var(--color-muted);
  font-size: 0.95rem;
  margin: 0 0 2rem;
}

.lesson__body {
  max-width: 44rem;
}

.callout {
  border-left: 4px solid var(--color-primary);
  background: var(--color-tint);
  border-radius: 0 8px 8px 0;
  padding: 1.1rem 1.3rem;
  margin: 1.6rem 0;
}

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

.media {
  margin: 1.75rem 0;
}

.media img {
  border-radius: var(--radius);
  width: 100%;
}

.media figcaption {
  margin-top: 0.5rem;
  font-size: 0.9rem;
  color: var(--color-muted);
  text-align: center;
}

.related {
  border-top: 1px solid var(--color-line);
  margin-top: 3.5rem;
  padding-top: 2.5rem;
}

.related ul {
  margin-top: 1.25rem;
}

.empty-state {
  border: 2px dashed var(--color-line);
  background: var(--color-surface);
  border-radius: var(--radius);
  padding: 2rem;
  color: var(--color-muted);
  text-align: center;
}

.empty-state__label {
  display: block;
  font-family: var(--font-head);
  color: var(--color-ink);
  font-size: 1.05rem;
  margin-bottom: 0.35rem;
}

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

.site-footer__inner {
  display: grid;
  gap: 1.25rem;
  align-items: start;
}

.site-footer__tagline {
  font-family: var(--font-head);
  font-size: 1.1rem;
  margin: 0;
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 1.25rem;
}

.site-footer__disclosure {
  color: var(--color-muted);
  font-size: 0.9rem;
  margin: 0;
}

@media (min-width: 640px) {
  .site-header__inner {
    flex-direction: row;
    align-items: center;
    gap: 0.5rem 1.25rem;
  }

  .site-nav {
    margin-left: auto;
  }

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

@media (min-width: 900px) {
  .lesson-layout {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 300px;
    gap: 2.5rem;
    align-items: start;
  }

  .lesson__side {
    position: sticky;
    top: 5rem;
  }

  .related ul {
    grid-template-columns: repeat(3, 1fr);
  }

  .site-footer__inner {
    grid-template-columns: 1fr auto 1fr;
    align-items: center;
  }

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

  .site-footer__disclosure {
    text-align: right;
  }
}

a:focus-visible {
  outline: 3px solid var(--color-primary-strong);
  outline-offset: 2px;
}

.skip-link:focus-visible {
  outline-color: #ffffff;
}

.site-nav__link {
  padding-top: 0.6rem;
  padding-bottom: 0.6rem;
}

.breadcrumb a {
  padding: 0.6rem 0;
}

.footer-nav a {
  padding: 0.5rem 0;
}

.site-logo {
  min-height: 44px;
}

.btn {
  cursor: pointer;
}

.consent-banner {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 50;
  padding: 1rem 0;
  background: var(--color-surface);
  border-top: 1px solid var(--color-line);
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.08);
}

.consent-banner--hidden {
  display: none;
}

.consent-banner__inner {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.75rem;
}

.consent-banner__text {
  margin: 0;
  max-width: 48rem;
  color: var(--color-muted);
  font-size: 0.95rem;
}

.consent-banner__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  flex-shrink: 0;
}

.consent-banner .btn {
  margin-top: 0;
  font-family: var(--font-body);
  font-size: 0.95rem;
}

.btn--ghost {
  background: transparent;
  color: var(--color-primary-strong);
  border: 2px solid var(--color-primary);
}

.btn--ghost:hover {
  background: var(--color-tint);
  color: var(--color-primary-strong);
}

@media (min-width: 720px) {
  .consent-banner__inner {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }
}

.site-logo__img {
  height: 32px;
  width: auto;
  max-width: 32px;
  border-radius: 50%;
  border: 1px solid var(--color-line);
  object-fit: cover;
}

.hero__banner {
  display: block;
  width: 100%;
  height: auto;
  border-radius: var(--radius);
  margin-bottom: 1.5rem;
}

.video-wrap {
  margin: 1.75rem 0;
}

.video-facade {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  width: 100%;
  aspect-ratio: 16 / 9;
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  background: var(--color-tint);
  color: var(--color-muted);
  cursor: pointer;
  font-family: var(--font-body);
  font-size: 0.95rem;
  padding: 0;
}

.video-facade:hover {
  border-color: var(--color-primary);
}

.video-facade__play {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--color-surface);
  border: 2px solid var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
}

.video-facade__play::before {
  content: "";
  width: 0;
  height: 0;
  margin-left: 4px;
  border-left: 12px solid var(--color-primary);
  border-top: 8px solid transparent;
  border-bottom: 8px solid transparent;
}

.video-embed {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  border: 0;
  border-radius: var(--radius);
}

.video-note {
  color: var(--color-primary-strong);
}

.ext-label {
  font-size: 0.8rem;
  font-weight: 400;
  color: var(--color-muted);
}

.site-nav__link:hover,
.site-nav__link:focus-visible {
  text-decoration: underline;
}

.lang-toggle {
  background: transparent;
  border: 1.5px solid var(--color-primary);
  color: var(--color-primary);
  border-radius: 999px;
  padding: 0.25rem 0.65rem;
  font-family: var(--font-body);
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  line-height: 1.3;
}

.lang-toggle:hover {
  background: var(--color-tint);
}

.lang-toggle:focus-visible {
  outline: 3px solid var(--color-primary-strong);
  outline-offset: 2px;
}

.lesson__notice {
  background: var(--color-tint);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  padding: 0.85rem 1.2rem;
  margin: 0 0 1.5rem;
  font-size: 0.95rem;
  color: var(--color-muted);
}

.footer-social {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 0.25rem;
}

.footer-social__link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border: 1.5px solid var(--color-line);
  border-radius: 50%;
  color: var(--color-muted);
  text-decoration: none;
}

.footer-social__link:hover,
.footer-social__link:focus-visible {
  color: var(--color-ink);
  border-color: var(--color-primary-strong);
}

.tier-badge {
  display: inline-block;
  padding: 0.2rem 0.75rem;
  border: 1.5px solid var(--color-primary-strong);
  border-radius: 999px;
  background: transparent;
  color: var(--color-primary-strong);
  font-size: 0.78rem;
  font-weight: 600;
  line-height: 1.35;
}

.lesson-card__tier {
  margin: 0 0 0.6rem;
}

.lesson__tier {
  margin: 0 0 1.25rem;
}

.lesson__builds-on {
  margin: -0.75rem 0 1.25rem;
  font-size: 0.95rem;
  color: var(--color-muted);
}

.lesson__builds-on a {
  color: var(--color-primary);
  font-weight: 600;
}

@media (min-width: 900px) {
  .footer-social {
    grid-column: 1 / -1;
    justify-content: center;
    margin-top: 0.5rem;
  }
}