:root {
  color-scheme: light;
  --ink: #10201f;
  --muted: #5c6b68;
  --paper: #f7f4ee;
  --panel: #ffffff;
  --line: rgba(16, 32, 31, 0.14);
  --accent: #0f766e;
  --accent-dark: #115e59;
  --gold: #b7791f;
  --deep: #102a2a;
  --shadow: 0 24px 70px rgba(16, 32, 31, 0.14);
}

* {
  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: 1.6;
}

a {
  color: inherit;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1rem clamp(1rem, 5vw, 4rem);
  border-bottom: 1px solid rgba(255, 255, 255, 0.16);
  background: rgba(16, 42, 42, 0.88);
  color: #fff;
  backdrop-filter: blur(16px);
}

.brand {
  font-weight: 800;
  letter-spacing: 0.02em;
}

.nav {
  display: flex;
  gap: 1rem;
  font-size: 0.94rem;
}

.nav a {
  color: rgba(255, 255, 255, 0.82);
  text-decoration: none;
}

.nav a:hover {
  color: #fff;
}

.hero {
  min-height: 78vh;
  display: grid;
  align-items: end;
  padding: 5.5rem clamp(1rem, 6vw, 5rem) 3.5rem;
  color: #fff;
  background:
    linear-gradient(180deg, rgba(12, 23, 23, 0.28), rgba(10, 20, 20, 0.8)),
    linear-gradient(120deg, rgba(15, 118, 110, 0.78), rgba(16, 42, 42, 0.76)),
    url("../images/cover.png") center / cover;
}

.hero-inner {
  width: min(980px, 100%);
}

.eyebrow {
  margin: 0 0 1rem;
  color: #f6d083;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hero h1 {
  max-width: 980px;
  margin: 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(2.2rem, 4.2vw, 3.9rem);
  line-height: 1.02;
  letter-spacing: 0;
}

.subtitle {
  max-width: 720px;
  margin: 1.35rem 0 0;
  color: rgba(255, 255, 255, 0.88);
  font-size: clamp(1.05rem, 2vw, 1.35rem);
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  margin-top: 2rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0.85rem 1.15rem;
  border-radius: 6px;
  background: var(--accent);
  color: #fff;
  font-weight: 800;
  text-decoration: none;
  box-shadow: 0 16px 35px rgba(15, 118, 110, 0.26);
}

.button:hover {
  background: var(--accent-dark);
}

.button.secondary {
  border: 1px solid rgba(255, 255, 255, 0.36);
  background: rgba(255, 255, 255, 0.1);
  box-shadow: none;
}

.section {
  padding: 5rem clamp(1rem, 6vw, 5rem);
}

.section.alt {
  background: #fff;
}

.section-inner {
  width: min(1120px, 100%);
  margin: 0 auto;
}

.split {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(280px, 1.1fr);
  gap: clamp(2rem, 5vw, 4rem);
  align-items: start;
}

h2 {
  margin: 0 0 1rem;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(2rem, 4vw, 3.1rem);
  line-height: 1.08;
  letter-spacing: 0;
}

.lead {
  margin: 0;
  color: var(--muted);
  font-size: 1.1rem;
}

.feature-list,
.chapter-list {
  display: grid;
  gap: 0.85rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.feature-list li,
.chapter-list li {
  padding: 1rem 0;
  border-bottom: 1px solid var(--line);
}

.feature-list strong,
.chapter-list strong {
  display: block;
  color: var(--deep);
}

.chapter-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem 2rem;
}

.footer {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 1rem;
  padding: 2rem clamp(1rem, 6vw, 5rem);
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.95rem;
}

.footer a {
  color: var(--accent-dark);
  font-weight: 700;
  text-decoration: none;
}

@media (max-width: 800px) {
  .site-header {
    align-items: flex-start;
    flex-direction: column;
  }

  .nav {
    flex-wrap: wrap;
  }

  .hero {
    min-height: 76vh;
    padding-top: 5rem;
  }

  .split,
  .chapter-grid {
    grid-template-columns: 1fr;
  }

  .section {
    padding-top: 3.5rem;
    padding-bottom: 3.5rem;
  }
}