/* ============================================================
   Actually Understanding AI — site stylesheet
   Themed after the book cover: white→blue gradient, navy ink,
   royal blue accent. Edit freely; changes appear on refresh.
   ============================================================ */

:root {
  --ink: #10151d;          /* near-black navy (cover title) */
  --paper: #fbfcfe;        /* cover top gradient */
  --sky: #aac2da;          /* cover bottom gradient */
  --accent: #2a5db0;       /* royal blue ("Actually" script / node) */
  --accent-dark: #1e4587;
  --muted: #5c6b7e;
  --rule: #d9e2ec;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
  font-family: Georgia, 'Times New Roman', serif;
  color: var(--ink);
  background: var(--paper);
  line-height: 1.65;
}

h1, h2, h3, .nav, .btn, .kicker {
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
}

a { color: var(--accent); }

.wrap { max-width: 980px; margin: 0 auto; padding: 0 24px; }

/* ---------- Header / nav ---------- */
header.site {
  border-bottom: 1px solid var(--rule);
  background: var(--paper);
}
.nav {
  display: flex; align-items: center; justify-content: space-between;
  padding: 18px 0; flex-wrap: wrap; gap: 12px;
}
.nav .brand {
  font-weight: 700; font-size: 1.05rem; letter-spacing: .02em;
  color: var(--ink); text-decoration: none;
}
.nav ul { display: flex; gap: 22px; list-style: none; }
.nav ul a {
  text-decoration: none; color: var(--muted); font-size: .95rem;
  text-transform: uppercase; letter-spacing: .08em; font-size: .82rem;
}
.nav ul a:hover, .nav ul a.active { color: var(--accent); }

/* ---------- Hero (cover-style gradient) ---------- */
.hero-band {
  background: linear-gradient(180deg, #fdfeff 0%, #e8eef6 55%, var(--sky) 100%);
  border-bottom: 1px solid var(--rule);
}
.hero {
  display: grid; grid-template-columns: 1fr 320px; gap: 56px;
  align-items: center; padding: 72px 0;
}
.kicker {
  text-transform: uppercase; letter-spacing: .22em; font-size: .78rem;
  color: var(--ink); font-weight: 600; margin-bottom: 16px;
}
.kicker::after { content: " ———"; color: var(--muted); }
.hero h1 { font-size: 2.7rem; line-height: 1.15; margin-bottom: 18px; letter-spacing: -.01em; }
.hero .sub {
  font-size: 1.25rem; color: var(--ink); margin-bottom: 30px;
  font-style: italic;   /* echoes "It's simpler than you think." */
}

/* Real cover image */
.cover-img {
  width: 100%; max-width: 320px; display: block; margin: 0 auto;
  border-radius: 3px;
  box-shadow: 0 24px 48px rgba(16, 21, 29, .28), 0 4px 10px rgba(16, 21, 29, .18);
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-block; padding: 14px 30px; border-radius: 6px;
  text-decoration: none; font-weight: 700; font-size: 1rem;
}
.btn.primary { background: var(--accent); color: #fff; }
.btn.primary:hover { background: var(--accent-dark); }
.btn.ghost { border: 2px solid var(--ink); color: var(--ink); margin-left: 12px; }
.btn.ghost:hover { background: var(--ink); color: #fff; }

/* ---------- Sections ---------- */
section.band { padding: 56px 0; border-top: 1px solid var(--rule); }
section.band:first-of-type { border-top: none; }
section.band h2 { font-size: 1.7rem; margin-bottom: 22px; }
.cols3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 30px; }
.cols3 h3 { font-size: 1.05rem; margin-bottom: 8px; color: var(--accent); }
.cols3 p { font-size: .97rem; color: var(--muted); }

blockquote.pull {
  font-size: 1.25rem; font-style: italic; color: var(--ink);
  border-left: 4px solid var(--accent); padding: 6px 0 6px 24px; margin: 30px 0;
}

/* ---------- TOC ---------- */
.toc-part { margin: 28px 0 10px; font-family: Helvetica, sans-serif;
  font-weight: 700; text-transform: uppercase; letter-spacing: .14em;
  font-size: .82rem; color: var(--accent); }
.toc-list { list-style: none; }
.toc-list li { padding: 6px 0; border-bottom: 1px dotted var(--rule); }
.toc-list .ch { color: var(--muted); font-size: .85rem; margin-right: 10px;
  font-family: Helvetica, sans-serif; }

/* ---------- Excerpt ---------- */
.excerpt { max-width: 720px; }
.excerpt p { margin-bottom: 18px; font-size: 1.05rem; }
.excerpt h3 { margin: 28px 0 12px; }

/* ---------- Contact ---------- */
.contact-card {
  background: #fff; border: 1px solid var(--rule); border-radius: 10px;
  padding: 36px; max-width: 560px;
  box-shadow: 0 6px 18px rgba(16, 21, 29, .06);
}
.contact-card p { margin-bottom: 16px; }

/* ---------- Footer (navy like the spine) ---------- */
footer.site {
  background: var(--ink); color: #b9c6d6;
  margin-top: 60px; padding: 30px 0; font-size: .9rem;
  font-family: Helvetica, sans-serif;
}
footer.site a { color: #dce6f2; }

/* ---------- Responsive ---------- */
@media (max-width: 760px) {
  .hero { grid-template-columns: 1fr; padding: 40px 0; }
  .cover-img { margin-top: 10px; max-width: 260px; }
  .cols3 { grid-template-columns: 1fr; }
  .hero h1 { font-size: 2.1rem; }
  .btn.ghost { margin-left: 0; margin-top: 12px; }
}