:root {
  --ink: #171717;
  --muted: #5b6470;
  --line: #e5e8ee;
  --paper: #ffffff;
  --soft: #f7f9fc;
  --soft-blue: #eef8ff;
  --red: #e3312d;
  --orange: #f28a00;
  --yellow: #f4d000;
  --green: #15995a;
  --blue: #0d86d4;
  --purple: #7d50b8;
  --shadow: 0 22px 60px rgba(21, 27, 38, 0.11);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.5;
}

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

:focus-visible {
  outline: 4px solid var(--blue);
  outline-offset: 4px;
}

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

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

h1 {
  margin-bottom: 20px;
  font-size: clamp(48px, 6.7vw, 90px);
  line-height: 0.96;
  letter-spacing: 0;
}

h2 {
  margin-bottom: 18px;
  font-size: clamp(34px, 5vw, 70px);
  line-height: 1;
  letter-spacing: 0;
}

h3 {
  margin-bottom: 12px;
  font-size: clamp(23px, 2.3vw, 32px);
  line-height: 1.08;
  letter-spacing: 0;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
  padding: 16px clamp(20px, 4vw, 64px);
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.94);
  backdrop-filter: blur(18px);
}

.skip-link {
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 100;
  padding: 12px 16px;
  border-radius: 6px;
  background: var(--ink);
  color: #fff;
  font-weight: 900;
  transform: translateY(-180%);
}

.skip-link:focus {
  transform: translateY(0);
}

.brand img {
  width: min(220px, 42vw);
  height: auto;
}

.menu-toggle {
  display: none;
  align-items: center;
  gap: 10px;
  min-height: 46px;
  padding: 9px 13px;
  border: 2px solid var(--ink);
  border-radius: 6px;
  background: #fff;
  color: var(--ink);
  font: inherit;
  font-weight: 900;
  cursor: pointer;
}

.menu-icon {
  display: grid;
  gap: 4px;
  width: 21px;
}

.menu-icon i {
  display: block;
  width: 100%;
  height: 2px;
  background: currentColor;
}

.main-nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 8px;
  font-size: 15px;
  font-weight: 850;
}

.main-nav a {
  padding: 10px 14px;
  border-radius: 999px;
}

.main-nav a:hover {
  background: var(--soft);
}

.hero {
  display: grid;
  grid-template-columns: minmax(340px, 1.02fr) minmax(0, 0.98fr);
  align-items: center;
  gap: clamp(28px, 5vw, 76px);
  padding: clamp(44px, 7vw, 92px) clamp(20px, 5vw, 76px) 56px;
  overflow: hidden;
}

.hero-copy {
  order: 2;
  max-width: 760px;
}

.eyebrow {
  margin: 0 0 14px;
  color: var(--blue);
  font-size: 14px;
  font-weight: 900;
  letter-spacing: 0;
  text-transform: uppercase;
}

.hero-lead,
.section-heading p,
.edu-copy p,
.documents p,
.social-section p,
.author-card p,
.awards-card p {
  color: var(--muted);
  font-size: clamp(19px, 2vw, 26px);
  line-height: 1.38;
}

.hero-actions,
.rules-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 30px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 54px;
  padding: 15px 22px;
  border: 2px solid var(--ink);
  border-radius: 999px;
  font-size: 17px;
  font-weight: 900;
  line-height: 1.1;
  transition: transform 180ms ease, box-shadow 180ms ease, background 180ms ease;
}

.button.primary {
  background: var(--ink);
  color: #fff;
}

.button.secondary {
  background: #fff;
}

.button:hover,
.link-list a:hover,
.edu-links a:hover,
.download-card:hover,
.social-links a:hover {
  transform: translateY(-2px);
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
  max-width: 720px;
  margin-top: 32px;
}

.hero-stats div {
  min-height: 118px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--soft);
}

.hero-stats strong {
  display: block;
  font-size: clamp(28px, 3.6vw, 46px);
  line-height: 1;
}

.hero-stats span {
  display: block;
  margin-top: 8px;
  color: var(--muted);
  font-weight: 850;
}

.hero-visual {
  position: relative;
  align-self: start;
  order: 1;
}

.box-art-8mln {
  width: auto;
  height: min(570px, calc(100svh - 220px));
  margin-right: auto;
  filter: drop-shadow(0 24px 42px rgba(21, 27, 38, 0.14));
}

.section,
.social-section,
.author-awards,
.link-panel,
.documents {
  scroll-margin-top: 112px;
}

.section {
  padding: 78px clamp(20px, 5vw, 76px);
}

.section-heading {
  max-width: 960px;
  margin-bottom: 36px;
}

.why-section,
.audience-section {
  background: var(--soft);
  border-block: 1px solid var(--line);
}

.feature-grid,
.audience-grid,
.rules-grid {
  display: grid;
  gap: 18px;
}

.feature-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.feature-card,
.audience-grid article,
.rules-grid article {
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.feature-card {
  min-height: 270px;
}

.feature-card p,
.audience-grid p,
.rules-grid p,
.how-to-hero p,
.line-explainers p {
  color: var(--muted);
  font-size: 18px;
}

.shape-mark {
  width: 54px;
  aspect-ratio: 1;
  margin-bottom: 24px;
}

.shape-mark.circle {
  background: var(--red);
  border-radius: 50%;
}

.shape-mark.square {
  background: var(--blue);
  border-radius: 6px;
}

.shape-mark.diamond {
  background: var(--green);
  transform: rotate(45deg);
  border-radius: 7px;
}

.shape-mark.star {
  background: var(--yellow);
  clip-path: polygon(50% 0, 61% 32%, 95% 20%, 76% 50%, 95% 80%, 61% 68%, 50% 100%, 39% 68%, 5% 80%, 24% 50%, 5% 20%, 39% 32%);
}

.rules-section,
.lines-section {
  background: #fff;
}

.how-to-hero {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(300px, 0.95fr);
  gap: clamp(26px, 4vw, 54px);
  align-items: center;
  margin-bottom: 22px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--soft);
}

.how-to-hero img {
  width: 100%;
  border-radius: 8px;
  box-shadow: 0 16px 34px rgba(25, 28, 35, 0.08);
}

.video-panel {
  overflow: hidden;
  margin: 22px 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #101010;
  box-shadow: 0 16px 34px rgba(25, 28, 35, 0.08);
}

.video-launch {
  position: relative;
  display: grid;
  width: 100%;
  aspect-ratio: 16 / 9;
  place-items: center;
  overflow: hidden;
  padding: 0;
  border: 0;
  background: #101010;
  color: #fff;
  cursor: pointer;
}

.video-launch img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.48;
}

.video-launch strong {
  position: relative;
  z-index: 1;
  margin-top: 112px;
  padding: 10px 16px;
  font-size: clamp(20px, 3vw, 34px);
  text-align: center;
  text-shadow: 0 2px 12px #000;
}

.play-icon {
  position: absolute;
  z-index: 1;
  width: 86px;
  aspect-ratio: 1;
  border-radius: 50%;
  background: var(--red);
  box-shadow: 0 12px 34px rgba(0, 0, 0, 0.28);
}

.play-icon::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 54%;
  border-top: 16px solid transparent;
  border-bottom: 16px solid transparent;
  border-left: 25px solid #fff;
  transform: translate(-50%, -50%);
}

.video-panel iframe {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  border: 0;
}

.video-external,
.video-fallback {
  display: block;
  padding: 14px 18px;
  background: #101010;
  color: #fff;
  font-weight: 850;
  text-align: center;
  text-decoration: underline;
}

.rules-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.rules-grid article {
  background: var(--soft);
}

.rules-grid span {
  display: grid;
  place-items: center;
  width: 44px;
  aspect-ratio: 1;
  margin-bottom: 18px;
  border-radius: 50%;
  background: var(--red);
  color: #fff;
  font-size: 24px;
  font-weight: 900;
}

.line-explainers {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}

.line-explainers article {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  box-shadow: 0 16px 34px rgba(25, 28, 35, 0.06);
}

.line-explainers img {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.line-explainers article > div {
  padding: 24px;
}

.audience-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.audience-grid article {
  border-top: 8px solid var(--blue);
}

.audience-grid article:nth-child(2) {
  border-top-color: var(--red);
}

.audience-grid article:nth-child(3) {
  border-top-color: var(--green);
}

.audience-grid article:nth-child(4) {
  border-top-color: var(--orange);
}

.social-section {
  display: grid;
  grid-template-columns: minmax(0, 0.92fr) minmax(320px, 1.08fr);
  gap: clamp(28px, 5vw, 70px);
  align-items: start;
  padding: 82px clamp(20px, 5vw, 76px);
  border-block: 1px solid var(--line);
  background: linear-gradient(90deg, rgba(13, 134, 212, 0.08), transparent 44%), #fff;
}

.social-links {
  display: grid;
  gap: 14px;
}

.social-links a {
  display: grid;
  gap: 8px;
  min-height: 126px;
  padding: 24px;
  border: 2px solid var(--line);
  border-radius: 8px;
  background: #fff;
  box-shadow: 0 16px 34px rgba(25, 28, 35, 0.06);
  transition: transform 180ms ease, border-color 180ms ease;
}

.social-links span,
.download-card small,
.link-list small {
  color: var(--muted);
  font-weight: 850;
}

.social-links strong {
  font-size: clamp(24px, 3vw, 36px);
  line-height: 1.05;
}

.social-links a:nth-child(1) {
  border-left: 8px solid var(--blue);
}

.social-links a:nth-child(2) {
  border-left: 8px solid var(--red);
}

.social-links a:nth-child(3) {
  border-left: 8px solid var(--yellow);
}

.edu-section {
  display: grid;
  grid-template-columns: minmax(320px, 0.95fr) minmax(0, 1.05fr);
  gap: clamp(28px, 5vw, 64px);
  align-items: center;
  background: #fff;
}

.section-art {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  box-shadow: var(--shadow);
}

.section-art img {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.edu-content {
  display: grid;
  gap: 26px;
}

.edu-links,
.link-list,
.download-cards {
  display: grid;
  gap: 12px;
}

.edu-links a,
.link-list a {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  padding: 20px 22px;
  border: 2px solid var(--line);
  border-radius: 8px;
  background: #fff;
  font-size: 21px;
  font-weight: 900;
  transition: transform 180ms ease, border-color 180ms ease;
}

.link-list a::after,
.edu-links a::after,
.site-footer a::after {
  content: "↗";
  flex: 0 0 auto;
  color: var(--blue);
}

.edu-links a:nth-child(1) { border-left: 8px solid var(--blue); }
.edu-links a:nth-child(2) { border-left: 8px solid var(--green); }
.edu-links a:nth-child(3) { border-left: 8px solid var(--red); }
.edu-links a:nth-child(4) { border-left: 8px solid var(--orange); }
.edu-links a:nth-child(5) { border-left: 8px solid var(--purple); }
.edu-links a:nth-child(6) { border-left: 8px solid var(--yellow); }

.author-awards {
  display: grid;
  gap: 34px;
  padding: 82px clamp(20px, 5vw, 76px);
  background: var(--soft);
  border-block: 1px solid var(--line);
}

.author-card,
.awards-card {
  display: grid;
  grid-template-columns: minmax(280px, 0.78fr) minmax(0, 1.22fr);
  gap: clamp(28px, 5vw, 64px);
  align-items: center;
}

.awards-card {
  grid-template-columns: minmax(0, 0.9fr) minmax(280px, 1.1fr);
  padding-top: 34px;
  border-top: 1px solid var(--line);
}

.author-card img,
.awards-card img {
  width: 100%;
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.intro-section {
  background: #fff;
}

.topic-banners {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
  margin-bottom: 42px;
}

.topic-banners figure {
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  box-shadow: 0 16px 34px rgba(25, 28, 35, 0.08);
}

.topic-banners img {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.topic-banners figcaption {
  padding: 18px 20px;
  font-size: 24px;
  font-weight: 900;
}

.link-panel {
  display: grid;
  grid-template-columns: minmax(240px, 0.65fr) minmax(0, 1.35fr);
  gap: clamp(24px, 4vw, 54px);
  padding: 78px clamp(20px, 5vw, 76px);
  border-block: 1px solid var(--line);
  background: var(--soft);
}

.documents {
  display: grid;
  grid-template-columns: minmax(0, 0.85fr) minmax(0, 1.15fr);
  gap: clamp(28px, 5vw, 72px);
  padding: 78px clamp(20px, 5vw, 76px);
  background: #fff;
}

.download-card {
  display: grid;
  grid-template-columns: 86px 1fr;
  align-items: center;
  gap: 20px;
  min-height: 128px;
  padding: 22px;
  border: 2px solid var(--line);
  border-radius: 8px;
  background: #fff;
  transition: transform 180ms ease, border-color 180ms ease;
}

.download-card span {
  display: grid;
  place-items: center;
  width: 70px;
  aspect-ratio: 1;
  border-radius: 8px;
  background: var(--ink);
  color: #fff;
  font-weight: 900;
}

.download-card strong {
  display: block;
  font-size: 22px;
  line-height: 1.15;
}

.site-footer {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  padding: 28px clamp(20px, 5vw, 76px);
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-weight: 900;
}

.site-footer p {
  margin: 0;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
}

@media (max-width: 1120px) {
  .feature-grid,
  .audience-grid,
  .rules-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .hero-stats {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 980px) {
  .hero,
  .how-to-hero,
  .social-section,
  .edu-section,
  .author-card,
  .awards-card,
  .link-panel,
  .documents {
    grid-template-columns: 1fr;
  }

  .hero-copy {
    order: 1;
  }

  .hero-visual {
    align-self: center;
    order: 2;
  }

  .box-art-8mln {
    width: min(570px, 100%);
    height: auto;
    margin: 0 auto;
  }
}

@media (max-width: 720px) {
  .site-header {
    align-items: center;
    flex-direction: row;
    gap: 14px;
    padding-block: 12px;
  }

  .main-nav {
    width: 100%;
    justify-content: flex-start;
  }

  .js .site-header {
    flex-wrap: wrap;
  }

  .js .menu-toggle {
    display: inline-flex;
    margin-left: auto;
  }

  .js .main-nav {
    display: none;
    flex-direction: column;
    align-items: stretch;
    padding-top: 10px;
    border-top: 1px solid var(--line);
  }

  .js .main-nav.is-open {
    display: flex;
  }

  .js .main-nav a {
    padding: 12px 8px;
    border-radius: 4px;
  }

  .hero {
    padding-top: 34px;
  }

  .feature-grid,
  .audience-grid,
  .rules-grid,
  .topic-banners,
  .line-explainers,
  .hero-stats {
    grid-template-columns: 1fr;
  }

  .hero-stats div {
    min-height: 0;
  }

  .link-list a,
  .edu-links a {
    align-items: flex-start;
    flex-direction: column;
    font-size: 19px;
  }

  .download-card {
    grid-template-columns: 1fr;
  }

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

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}