:root {
  color-scheme: light;
  background: #f7fcff;
  color: #18313a;
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  min-height: 100%;
  margin: 0;
}

body {
  background:
    linear-gradient(180deg, #f7fcff 0%, #ffffff 42%, #eefbff 100%);
}

a {
  color: inherit;
  text-decoration-color: #38c8e8;
  text-underline-offset: 0.18em;
}

.topbar,
.footer,
.shell {
  width: min(100% - 32px, 1120px);
  margin: 0 auto;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 22px 0;
}

.brand {
  display: inline-flex;
  width: 148px;
  align-items: center;
  text-decoration: none;
}

.brand img {
  width: 100%;
  height: auto;
  display: block;
}

.topbar nav,
.footer nav {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  color: #315a66;
  font-size: 14px;
}

.shell {
  padding: 0 0 72px;
}

.hero {
  display: grid;
  gap: 18px;
  padding: clamp(8px, 1.8vw, 18px) 0 clamp(34px, 5vw, 58px);
}

.hero.compact {
  padding-top: 36px;
}

.eyebrow,
.category,
.meta {
  margin: 0;
  color: #227488;
  font-size: 13px;
}

.eyebrow,
.category {
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  overflow-wrap: anywhere;
}

h1,
h2,
h3 {
  margin: 0;
  color: #15191f;
  letter-spacing: 0;
}

h1 {
  max-width: 1120px;
  font-size: clamp(32px, 4.5vw, 52px);
  line-height: 1.04;
}

h2 {
  font-size: clamp(28px, 4vw, 42px);
  line-height: 1.06;
}

h3 {
  font-size: 22px;
  line-height: 1.18;
}

.lead {
  max-width: 1120px;
  margin: 0;
  color: #28333d;
  font-size: clamp(24px, 3.4vw, 44px);
  line-height: 1.14;
}

.disclosure {
  max-width: 760px;
  margin: 0;
  padding: 14px 16px;
  border-left: 4px solid #11b7d7;
  background: #e7faff;
  color: #204d59;
  font-size: 15px;
  line-height: 1.45;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.section {
  padding: 52px 0 0;
}

.section-head {
  display: grid;
  gap: 10px;
  margin-bottom: 22px;
}

.book-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.book-card {
  min-height: 260px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 22px;
  border: 1px solid #c7f1fb;
  border-radius: 8px;
  background: #ffffff;
  box-shadow: 0 18px 45px rgb(20 174 207 / 0.08);
}

.book-cover {
  width: 100%;
  aspect-ratio: 3 / 4;
  object-fit: contain;
  object-position: center;
  display: block;
  padding: 12px;
  border-radius: 6px;
  background: #f4fbfd;
}

.book-card p {
  margin: 0;
  color: #37444f;
  line-height: 1.55;
}

.category-list {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.category-list a,
.button {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  padding: 13px 16px;
  border-radius: 6px;
  border: 1px solid #8de7f5;
  background: #e7faff;
  color: #07576a;
  font-weight: 800;
  text-align: center;
  text-decoration: none;
}

.article {
  max-width: 780px;
  padding: 42px 0 24px;
}

.book-hero {
  display: grid;
  grid-template-columns: minmax(160px, 220px) minmax(0, 1fr);
  gap: 28px;
  align-items: start;
}

.book-hero .book-cover {
  position: sticky;
  top: 18px;
}

.article h1 {
  margin: 8px 0 8px;
  font-size: clamp(40px, 7vw, 66px);
}

.article section {
  margin-top: 34px;
}

.article h2 {
  margin-bottom: 10px;
  font-size: 24px;
}

.article p,
.article li {
  color: #2e3a44;
  font-size: 18px;
  line-height: 1.68;
}

.article ul {
  padding-left: 22px;
}

.audience-list {
  display: grid;
  gap: 10px;
  padding-left: 0;
  list-style: none;
}

.audience-list li {
  padding: 12px 14px;
  border: 1px solid #c7f1fb;
  border-radius: 8px;
  background: #f6fcff;
}

.footer {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px 24px;
  padding: 28px 0 38px;
  border-top: 1px solid #c7f1fb;
  color: #315a66;
}

.footer p {
  margin: 0;
}

.affiliate-disclosure {
  max-width: 620px;
  color: #315a66;
  font-size: 13px;
  line-height: 1.2;
  text-align: right;
}

@media (max-width: 860px) {
  .topbar,
  .footer {
    align-items: flex-start;
    grid-template-columns: 1fr;
  }

  .book-grid,
  .category-list {
    grid-template-columns: 1fr;
  }

  .book-hero {
    grid-template-columns: 1fr;
  }

  .book-hero .book-cover {
    position: static;
    max-width: 220px;
  }
}

@media (max-width: 520px) {
  .topbar,
  .footer,
  .shell {
    width: min(100% - 24px, 1120px);
  }

  .shell {
    padding-top: 14px;
  }

  .hero {
    padding-top: 26px;
  }

  .book-card {
    min-height: auto;
  }
}