:root {
  --ink: #17202a;
  --muted: #5e6b78;
  --line: #d8e0e8;
  --paper: #f7fafc;
  --panel: #ffffff;
  --green: #1f7a5a;
  --blue: #245d8f;
  --gold: #b7791f;
  --soft-green: #e9f6f0;
  --soft-blue: #eaf2fb;
  --soft-gold: #fff4df;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  color: var(--ink);
  background: var(--paper);
  line-height: 1.65;
}

a {
  color: var(--green);
  font-weight: 700;
}

.site-header {
  border-bottom: 1px solid var(--line);
  background: #fff;
}

.nav {
  width: min(980px, calc(100% - 32px));
  min-height: 72px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: var(--ink);
  font-weight: 800;
  text-decoration: none;
}

.brand-mark {
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border-radius: 8px;
  background: var(--green);
  color: #fff;
  font-weight: 900;
}

.nav-link {
  color: var(--green);
  text-decoration: none;
}

main {
  width: min(980px, calc(100% - 32px));
  margin: 0 auto;
}

.article-hero {
  padding: 64px 0 32px;
}

.eyebrow {
  display: inline-flex;
  padding: 7px 10px;
  border-radius: 6px;
  background: var(--soft-green);
  color: var(--green);
  font-size: 13px;
  font-weight: 800;
}

h1 {
  max-width: 860px;
  margin: 18px 0 14px;
  font-size: clamp(38px, 6vw, 64px);
  line-height: 1;
  letter-spacing: 0;
}

.lede {
  max-width: 760px;
  margin: 0;
  color: #334155;
  font-size: 20px;
}

.article-image {
  width: min(980px, calc(100% - 32px));
  margin: 0 auto 10px;
}

.article-image img {
  width: 100%;
  height: clamp(260px, 42vw, 460px);
  display: block;
  object-fit: cover;
  border-radius: 8px;
  border: 1px solid var(--line);
}

.content {
  display: grid;
  grid-template-columns: 1fr 280px;
  gap: 34px;
  align-items: start;
  padding: 24px 0 72px;
}

.article-body,
.sidebar-card {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.article-body {
  padding: 32px;
}

.article-body h2 {
  margin: 34px 0 10px;
  font-size: 30px;
  line-height: 1.15;
}

.article-body h2:first-child {
  margin-top: 0;
}

.article-body p {
  margin: 0 0 16px;
  color: #334155;
}

.article-body ul {
  margin: 0 0 22px;
  padding-left: 22px;
  color: #334155;
}

.example {
  margin: 24px 0;
  padding: 18px;
  border-left: 4px solid var(--blue);
  border-radius: 8px;
  background: var(--soft-blue);
}

.amazon-button {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  margin: 8px 0 20px;
  padding: 12px 18px;
  border-radius: 7px;
  background: var(--green);
  color: #fff;
  font-weight: 800;
  text-decoration: none;
}

.book-tile {
  width: 100%;
  aspect-ratio: 3 / 4;
  display: grid;
  place-items: center;
  padding: 20px;
  border-radius: 8px;
  background: linear-gradient(145deg, var(--soft-blue), var(--soft-green));
  color: var(--ink);
  font-size: 24px;
  font-weight: 900;
  text-align: center;
}

.book-directory {
  display: grid;
  gap: 16px;
}

.book-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 18px;
  align-items: start;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.book-row h2 {
  margin: 0 0 6px;
  font-size: 22px;
}

.book-row p {
  margin: 0;
  color: #334155;
}

.book-meta {
  display: block;
  margin-bottom: 4px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 800;
  text-transform: uppercase;
}

.sidebar {
  display: grid;
  gap: 16px;
  position: sticky;
  top: 16px;
}

.sidebar-card {
  padding: 20px;
}

.sidebar-card h2 {
  margin: 0 0 10px;
  font-size: 20px;
}

.sidebar-card ul {
  margin: 0;
  padding-left: 18px;
}

footer {
  padding: 34px 0;
  border-top: 1px solid var(--line);
  background: #fff;
  color: var(--muted);
}

.footer-inner {
  width: min(980px, calc(100% - 32px));
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  font-size: 14px;
}

.footer-note {
  width: 100%;
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 12px;
}

@media (max-width: 820px) {
  .nav {
    align-items: flex-start;
    flex-direction: column;
    padding: 14px 0;
  }

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

  .sidebar {
    position: static;
  }

  .article-body {
    padding: 22px;
  }
}