/* ============================================================
   AI CoS landing — shared base styles
   Loaded by: course, book, subscribed, confirmed, install,
   and all /install/<slug> detail pages.
   index.html is intentionally self-contained (bespoke nav + hero).
   Page-specific rules live in each page's inline <style>, which is
   loaded AFTER this file and therefore overrides it on conflict.
   ============================================================ */

* { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --bg: #0a0a0a;
  --surface: #161616;
  --border: #2a2a2a;
  --border-bright: #3a3a3a;
  --text: #f5f5f4;
  --text-2: #a1a1aa;
  --text-3: #71717a;
  --accent: #ec4899;
  --accent-dim: rgba(236, 72, 153, 0.15);
  --max-w: 1100px;
  --font-mono: "Geist Mono", ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --font-sans: "Geist", -apple-system, BlinkMacSystemFont, "Inter", "Segoe UI", system-ui, sans-serif;
}

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a { color: var(--accent); text-decoration: none; }
a:hover { opacity: 0.85; }

h1 { font-size: clamp(36px, 5vw, 56px); font-weight: 700; line-height: 1.1; letter-spacing: -0.02em; margin-bottom: 20px; }
h2 { font-size: clamp(24px, 3vw, 32px); font-weight: 700; line-height: 1.2; letter-spacing: -0.01em; margin-bottom: 16px; }

/* Nav */
nav {
  border-bottom: 1px solid var(--border);
  padding: 18px 24px;
  background: rgba(10, 10, 10, 0.85);
  backdrop-filter: blur(8px);
  position: sticky; top: 0; z-index: 50;
}
nav .inner {
  max-width: var(--max-w); margin: 0 auto;
  display: flex; justify-content: space-between; align-items: center; gap: 16px;
}
nav .brand { font-weight: 700; font-size: 15px; letter-spacing: -0.01em; font-family: var(--font-mono); text-transform: uppercase; color: var(--text); text-decoration: none; transition: opacity 0.15s; }
nav a.brand:hover { opacity: 0.75; }
nav .brand .accent { color: var(--accent); }
nav .links { display: flex; gap: 22px; align-items: center; }
nav .links a { color: var(--text-2); font-size: 14px; font-family: var(--font-mono); }
nav .links a:hover { color: var(--text); }
nav .links a.cta-btn {
  background: var(--accent); color: #0a0a0a;
  padding: 8px 14px; border-radius: 6px;
  font-weight: 600; font-family: var(--font-sans);
  display: inline-flex; align-items: center; gap: 6px;
}
nav .links a.cta-btn:hover { opacity: 0.9; }
.gh-icon { width: 16px; height: 16px; }
nav .links a.cta-btn .gh-icon { fill: #0a0a0a; }

/* Main */
main { flex: 1; }

/* Footer */
footer {
  border-top: 1px solid var(--border);
  padding: 40px 24px;
  margin-top: 40px;
}
footer .inner {
  max-width: var(--max-w); margin: 0 auto;
  display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 16px;
  color: var(--text-3); font-size: 14px;
}
footer .links { display: flex; gap: 20px; flex-wrap: wrap; }
@media (max-width: 720px) {
  footer .inner { flex-direction: column; align-items: flex-start; gap: 12px; }
  footer .links { gap: 12px 16px; }
}
footer a { color: var(--text-2); }
footer a:hover { color: var(--accent); }
footer .links a { display: inline-flex; align-items: center; gap: 6px; }
footer .credit {
  text-align: center;
  margin-top: 20px;
  font-family: var(--font-mono);
  color: var(--text-3);
  font-size: 12px;
  letter-spacing: 0.04em;
}