:root {
  --bg: #0f1320;
  --bg-soft: #17213a;
  --card: #1c2742;
  --text: #f3f6ff;
  --muted: #b8c3de;
  --line: #2e3a5a;
  --accent: #4ec2ff;
  --accent-strong: #15a8f6;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  font-family: "Manrope", system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at 12% 0%, rgba(78, 194, 255, 0.17), transparent 35%),
    linear-gradient(180deg, var(--bg), #0a0f19 60%);
  line-height: 1.55;
}

a {
  color: inherit;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 24px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  backdrop-filter: blur(8px);
  background: rgba(12, 18, 30, 0.82);
}

.brand {
  text-decoration: none;
  font-weight: 800;
  letter-spacing: 0.02em;
}

nav {
  display: flex;
  gap: 18px;
}

nav a {
  text-decoration: none;
  color: var(--muted);
  font-weight: 600;
}

main,
.site-footer {
  width: min(1040px, calc(100% - 40px));
  margin: 0 auto;
}

.hero {
  padding: 72px 0 26px;
}

.hero h1 {
  margin: 8px 0 10px;
  font-family: "Source Serif 4", Georgia, serif;
  font-size: clamp(2rem, 5vw, 3.4rem);
  line-height: 1.06;
}

.hero p {
  margin: 0;
  max-width: 66ch;
  color: var(--muted);
}

.eyebrow,
.kicker,
.book-num {
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-weight: 800;
  font-size: 0.72rem;
  color: var(--accent);
}

.section {
  padding: 28px 0;
}

.section-head h2 {
  margin: 8px 0 0;
  font-family: "Source Serif 4", Georgia, serif;
  font-size: clamp(1.5rem, 3.8vw, 2.3rem);
}

.book-grid {
  margin-top: 18px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.book-card {
  background: linear-gradient(170deg, var(--card), var(--bg-soft));
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 18px;
}

.book-cover {
  width: 100%;
  aspect-ratio: 2 / 3;
  object-fit: cover;
  border-radius: 10px;
  border: 1px solid rgba(255, 255, 255, 0.12);
  box-shadow: 0 8px 18px rgba(0, 0, 0, 0.24);
  margin-bottom: 12px;
}

.book-card h3 {
  margin: 6px 0 10px;
  font-family: "Source Serif 4", Georgia, serif;
  font-size: 1.4rem;
  line-height: 1.15;
}

.book-desc {
  margin: 0 0 0.9rem;
  color: var(--muted);
  line-height: 1.45;
}

.btn {
  display: inline-block;
  padding: 10px 14px;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 700;
  background: linear-gradient(120deg, var(--accent), var(--accent-strong));
  color: #04111b;
}

.btn.is-disabled {
  opacity: 0.74;
  pointer-events: none;
}

.section-story p {
  color: var(--muted);
  max-width: 70ch;
}

.site-footer {
  margin-top: 30px;
  padding: 34px 0 50px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.email-link {
  display: inline-block;
  margin-top: 6px;
  font-weight: 700;
  text-decoration: none;
}

.copyright {
  margin-top: 20px;
  color: var(--muted);
  font-size: 0.9rem;
}

@media (max-width: 760px) {
  nav {
    gap: 10px;
    font-size: 0.93rem;
  }

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