/* Building AI Applications: site styles.
   Matches the KomGIS homepage (../index.html): near-black background, hairline borders,
   heavy tight headings, uppercase small labels and a single lime accent. */
:root {
  --bg: #0c0c0b;
  --surface: #131312;
  --line: #252522;
  --text: #f2f0eb;
  --muted: #7a7870;
  --lime: #c6f135;
  --lime-hover: #d4ff3a;
  --on-lime: #0c0c0b;
  --white: #ffffff;
  --max: 1200px;
  --r: 4px;
  --font: 'Inter', Segoe UI, Arial, sans-serif;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}
img, video { max-width: 100%; display: block; }
a { color: var(--lime); text-decoration: none; transition: .15s; }
a:hover { color: var(--text); }
:focus-visible { outline: 2px solid var(--lime); outline-offset: 3px; border-radius: var(--r); }
h1, h2, h3 { font-weight: 800; letter-spacing: -0.04em; line-height: 1.1; text-wrap: balance; margin: 0; }
.muted { color: var(--muted); }
.grad { color: var(--lime); }

/* One accent everywhere: overrides the per-chapter colours set inline in the HTML */
.comp, .post-card, .video-card, .post { --c: var(--lime) !important; }

.wrap { width: min(var(--max), calc(100% - 56px)); margin: 0 auto; }
.wrap.narrow { max-width: 780px; }
.skip { position: absolute; left: -999px; }
.skip:focus { left: 16px; top: 12px; z-index: 60; background: var(--surface); padding: 8px 14px; }

/* ---------------------------------------------------------------- header / footer */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(12, 12, 11, .95); backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; gap: 16px; min-height: 68px; }
.brand {
  display: flex; align-items: center; gap: 10px; color: var(--text);
  font-size: 1.05rem; font-weight: 900; letter-spacing: .12em; text-transform: uppercase;
}
.brand:hover { color: var(--text); }
.brand-mark { width: 8px; height: 8px; border-radius: 50%; background: var(--lime); font-size: 0; overflow: hidden; flex-shrink: 0; }
.site-nav { display: flex; align-items: center; gap: 32px; font-size: .85rem; letter-spacing: .06em; text-transform: uppercase; }
.site-nav a { color: var(--muted); }
.site-nav a:hover, .site-nav a[aria-current="page"] { color: var(--text); }
.site-nav .nav-cta {
  padding: 9px 20px; background: var(--lime); color: var(--on-lime); border-radius: var(--r);
  font-weight: 800; letter-spacing: .04em;
}
.site-nav .nav-cta:hover { background: var(--lime-hover); color: var(--on-lime); }

.site-footer { border-top: 1px solid var(--line); margin-top: 0; }
.footer-inner { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 18px; padding-block: 32px; font-size: .82rem; letter-spacing: .04em; }
.footer-title { font-weight: 700; color: var(--text); }
.footer-links { display: flex; flex-wrap: wrap; gap: 24px; align-items: center; }
.footer-links a { color: var(--muted); text-transform: uppercase; }
.footer-links a:hover { color: var(--text); }

/* ---------------------------------------------------------------- shared */
.kicker {
  font-size: .78rem; font-weight: 400; letter-spacing: .25em; text-transform: uppercase;
  color: var(--muted); margin: 0 0 20px;
  display: flex; align-items: center; gap: 14px;
}
.kicker::before { content: ""; width: 32px; height: 1px; background: var(--muted); flex-shrink: 0; }
.kicker a { color: inherit; }
.kicker a:hover { color: var(--text); }
.lead { font-size: 1.25rem; color: var(--text); margin: 20px 0 0; max-width: 60ch; }
.section { padding-block: 72px; border-bottom: 1px solid var(--line); }
.section.tight { padding-top: 8px; }
.section-head { margin-bottom: 40px; display: grid; gap: 6px; }
.section-head h2 { font-size: clamp(1.8rem, 3vw, 2.8rem); }
.section-head p { margin: 8px 0 0; }
.section-head .kicker { margin-bottom: 12px; }
.section-head.row { display: flex; align-items: end; justify-content: space-between; gap: 16px; flex-wrap: wrap; }
.more { font-size: .85rem; letter-spacing: .06em; text-transform: uppercase; }

.actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 36px; }
.btn {
  display: inline-flex; align-items: center; gap: 10px; padding: 14px 28px; border-radius: var(--r);
  font-weight: 700; font-size: .95rem; letter-spacing: .01em; color: var(--muted);
  border: 1px solid var(--line); background: transparent;
}
.btn:hover { border-color: var(--text); color: var(--text); }
.btn-primary { background: var(--lime); color: var(--on-lime); border: 0; }
.btn-primary:hover { background: var(--lime-hover); color: var(--on-lime); }

/* ---------------------------------------------------------------- hero */
.hero { padding-block: 72px 100px; border-bottom: 1px solid var(--line); }
.hero-inner { display: grid; grid-template-columns: 1.2fr .8fr; gap: 64px; align-items: center; }
.hero-text { min-width: 0; }
.hero h1 { font-size: clamp(3rem, 6.5vw, 6.2rem); font-weight: 900; letter-spacing: -0.055em; line-height: 1.04; }
.hero h1 .grad { display: block; }
.hero .lead { font-weight: 700; letter-spacing: -.02em; }
.hero-copy { color: var(--muted); max-width: 58ch; margin: 18px 0 0; font-size: 1.05rem; line-height: 1.7; }
.facts {
  display: grid; grid-template-columns: repeat(3, 1fr); list-style: none; padding: 0; margin: 48px 0 0;
  border-top: 1px solid var(--line); font-size: .88rem; color: var(--muted);
}
.facts li { padding: 24px 24px 0 0; }
.facts li + li { padding-left: 24px; border-left: 1px solid var(--line); }
.facts strong { display: block; font-size: 3rem; color: var(--lime); font-weight: 900; letter-spacing: -.06em; font-variant-numeric: tabular-nums; line-height: 1; margin-bottom: 8px; }
.hero-cover img { width: 100%; height: auto; border-radius: var(--r); border: 1px solid var(--line); }

/* ---------------------------------------------------------------- video */
.video { width: 100%; aspect-ratio: 16 / 9; height: auto; border-radius: 8px; background: #000; border: 1px solid var(--line); }
.video-large { max-width: 900px; }
.video-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 40px 32px; }
.video-card { margin: 0; scroll-margin-top: 90px; }
.video-card figcaption { display: flex; gap: 14px; align-items: flex-start; margin-top: 14px; font-size: 1rem; line-height: 1.4; font-weight: 700; letter-spacing: -.02em; }
.video-card figcaption > span:nth-child(2) { flex: 1; min-width: 0; }
.video-card figcaption .comp-n { font-weight: 400; letter-spacing: .1em; color: var(--muted); }
.video-card figcaption .muted { font-weight: 400; letter-spacing: 0; font-size: .9rem; }
.video-card figcaption a { font-size: .78rem; font-weight: 400; letter-spacing: .1em; text-transform: uppercase; white-space: nowrap; }

/* ---------------------------------------------------------------- components grid */
/* A two-column table of contents in the homepage's ruled-grid style: number | title, tagline and links */
.comp-grid {
  list-style: none; padding: 0; margin: 0;
  display: grid; grid-template-columns: repeat(2, minmax(0, 1fr));
  border-top: 1px solid var(--line);
}
.comp {
  padding: 32px 28px 30px 0; border-bottom: 1px solid var(--line); transition: .15s;
  display: grid; grid-template-columns: 64px minmax(0, 1fr); column-gap: 16px; row-gap: 6px; align-content: start;
}
.comp:nth-child(even) { padding-left: 28px; padding-right: 0; border-left: 1px solid var(--line); }
.comp:hover h3 { color: var(--lime); }
.comp-n { font-size: .82rem; color: var(--muted); letter-spacing: .1em; font-variant-numeric: tabular-nums; }
.comp .comp-n { grid-row: 1 / span 3; font-size: 1.2rem; line-height: 1.3; }
.comp h3 { font-size: 1.3rem; letter-spacing: -.03em; transition: .15s; }
.comp p { margin: 0; color: var(--muted); font-size: .95rem; line-height: 1.6; }
.comp-links { display: flex; flex-wrap: wrap; gap: 6px 20px; margin-top: 10px; font-size: .75rem; letter-spacing: .12em; text-transform: uppercase; }

/* ---------------------------------------------------------------- posts */
.post-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(min(100%, 320px), 1fr));
  border-top: 1px solid var(--line); border-left: 1px solid var(--line);
}
.post-card {
  padding: 36px 28px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line);
  display: flex; flex-direction: column; gap: 12px; transition: .15s;
}
.post-card:hover { background: var(--surface); }
.post-card h3 { font-size: 1.2rem; letter-spacing: -.02em; line-height: 1.3; }
.post-card h3 a { color: var(--text); }
.post-card:hover h3 a, .post-card h3 a:hover { color: var(--lime); }
.post-card p { margin: 0; color: var(--muted); font-size: .9rem; line-height: 1.6; }
.post-card p:nth-last-child(1) { margin-top: auto; }
.post-meta { font-size: .75rem; letter-spacing: .15em; text-transform: uppercase; color: var(--muted); display: flex; align-items: center; gap: 10px; margin: 0; }
.post-meta.muted { color: var(--muted); }
.dot { width: 8px; height: 8px; border-radius: 50%; background: var(--lime); flex-shrink: 0; }

.page-head { padding-block: 72px 48px; }
.page-head h1 { font-size: clamp(2.6rem, 6vw, 5rem); font-weight: 900; letter-spacing: -.055em; }
.page-head .lead { color: var(--muted); font-size: 1.05rem; line-height: 1.7; }

.post-head { padding-block: 72px 32px; }
.post-head h1 { font-size: clamp(2.2rem, 5vw, 3.6rem); font-weight: 900; letter-spacing: -.05em; }
.post-head .lead { color: var(--muted); font-size: 1.1rem; line-height: 1.7; }
.post-head .post-meta { margin-top: 20px; display: block; }
.post-video { margin: 8px 0 48px; }
.post-video figcaption { font-size: .75rem; letter-spacing: .15em; text-transform: uppercase; margin-top: 10px; }

.prose { font-size: 1.05rem; line-height: 1.75; }
.prose h2 { font-size: 1.6rem; letter-spacing: -.03em; margin: 48px 0 14px; }
.prose p { margin: 0 0 18px; }
.prose ul, .prose ol { padding-left: 1.3em; margin: 0 0 20px; }
.prose li { margin-bottom: 8px; }
.prose li::marker { color: var(--lime); }
.prose strong { font-weight: 700; color: var(--white); }
.prose code { font-family: ui-monospace, Consolas, monospace; font-size: .88em; background: var(--surface); border: 1px solid var(--line); padding: 1px 6px; border-radius: var(--r); }
.prose table { width: 100%; border-collapse: collapse; margin: 8px 0 26px; font-size: .92rem; display: block; overflow-x: auto; border-top: 1px solid var(--line); }
.prose th, .prose td { text-align: left; padding: 12px 14px; border-bottom: 1px solid var(--line); vertical-align: top; }
.prose th { font-size: .72rem; letter-spacing: .2em; text-transform: uppercase; color: var(--muted); font-weight: 400; }

.book-cta {
  display: flex; gap: 28px; align-items: center; margin: 56px 0 40px; padding: 28px;
  border-radius: 8px; background: var(--surface); border: 1px solid var(--line);
}
.book-cta img { width: 110px; height: auto; border-radius: var(--r); border: 1px solid var(--line); flex-shrink: 0; }
.book-cta h2 { font-size: 1.4rem; }
.book-cta p { margin: 6px 0 18px; font-size: .95rem; }

.pager { display: grid; grid-template-columns: 1fr 1fr; border-top: 1px solid var(--line); margin-bottom: 48px; }
.pager a {
  display: flex; flex-direction: column; gap: 6px; padding: 24px 24px 24px 0;
  border-bottom: 1px solid var(--line); color: var(--text); font-size: 1rem; line-height: 1.4; font-weight: 700; letter-spacing: -.02em;
}
.pager a .muted { font-size: .72rem; font-weight: 400; letter-spacing: .2em; text-transform: uppercase; }
.pager a:hover { color: var(--lime); }
.pager .next { text-align: right; padding: 24px 0 24px 24px; border-left: 1px solid var(--line); }

/* ---------------------------------------------------------------- closing CTA */
.section.cta { border-bottom: 0; }
.cta-inner {
  text-align: center; padding: 72px 24px; border-radius: 8px; display: grid; justify-items: center; gap: 12px;
  background: var(--surface); border: 1px solid var(--line);
}
.cta-inner h2 { font-size: clamp(2rem, 4vw, 3.8rem); font-weight: 900; letter-spacing: -.05em; line-height: 1; }
.cta-inner p { margin: 8px 0 0; }
.cta-inner .actions { justify-content: center; margin-top: 24px; }

/* ---------------------------------------------------------------- small screens */
@media (max-width: 1020px) {
  .comp-grid, .video-grid { grid-template-columns: 1fr; }
  .comp, .comp:nth-child(even) { padding-left: 0; padding-right: 0; border-left: 0; }
  .hero-inner { grid-template-columns: 1fr; gap: 48px; }
  .hero-cover { max-width: 360px; }
  .section { padding-block: 56px; }
  .pager { grid-template-columns: 1fr; }
  .pager .next { text-align: left; padding-left: 0; border-left: 0; }
  .book-cta { flex-direction: column; align-items: flex-start; }
}
@media (max-width: 640px) {
  .wrap { width: min(var(--max), calc(100% - 32px)); }
  .hero { padding-block: 40px 60px; }
  .hero h1 { font-size: clamp(2.6rem, 11vw, 4rem); }
  .header-inner { flex-wrap: wrap; padding-block: 14px; gap: 10px 16px; }
  .brand { font-size: .82rem; letter-spacing: .08em; }
  .site-nav { gap: 18px; font-size: .78rem; flex-wrap: wrap; }
  .site-nav .nav-cta { padding: 7px 14px; }
  .facts strong { font-size: 2.2rem; }
  .facts li + li { padding-left: 16px; }
  .facts li { padding-right: 16px; }
  .footer-inner { flex-direction: column; align-items: flex-start; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}