/* ============================================================
   AI Handbooks — ai.zenoagi.com portal
   Editorial "field guide" dark theme
   Type: Fraunces (display) · Newsreader (body) · IBM Plex Mono
   ============================================================ */

:root {
  --ink: #0b0b10;
  --ink-2: #131320;
  --ink-3: #1a1a2b;
  --line: rgba(244, 241, 234, 0.09);
  --line-strong: rgba(244, 241, 234, 0.16);
  --paper: #f4f1ea;
  --paper-dim: rgba(244, 241, 234, 0.66);
  --paper-faint: rgba(244, 241, 234, 0.42);
  --amber: #ffb224;
  --amber-soft: rgba(255, 178, 36, 0.14);
  --topbar-bg: rgba(11, 11, 16, 0.72);
  --glow-amber: rgba(255, 178, 36, 0.13);
  --glow-violet: rgba(120, 110, 255, 0.07);
  --noise-opacity: 0.05;
  --serif: "Fraunces", Georgia, serif;
  --body: "Newsreader", Georgia, serif;
  --mono: "IBM Plex Mono", "SFMono-Regular", Consolas, monospace;
  --max: 1200px;
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

/* ---------- light mode ---------- */

:root[data-theme="light"] {
  --ink: #f5f2ea;
  --ink-2: #fffdf8;
  --ink-3: #ebe6d9;
  --line: rgba(24, 24, 32, 0.10);
  --line-strong: rgba(24, 24, 32, 0.22);
  --paper: #191921;
  --paper-dim: rgba(25, 25, 33, 0.70);
  --paper-faint: rgba(25, 25, 33, 0.46);
  --amber: #a06d00;
  --amber-soft: rgba(160, 109, 0, 0.12);
  --topbar-bg: rgba(245, 242, 234, 0.82);
  --glow-amber: rgba(255, 178, 36, 0.25);
  --glow-violet: rgba(120, 110, 255, 0.10);
  --noise-opacity: 0.035;
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--ink);
  color: var(--paper);
  font-family: var(--body);
  font-size: 17px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

::selection { background: var(--amber); color: var(--ink); }

/* ---------- atmosphere ---------- */

.bg-grid {
  position: fixed; inset: 0; z-index: -3; pointer-events: none;
  background-image:
    linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 56px 56px;
  mask-image: radial-gradient(ellipse 90% 70% at 50% 0%, #000 30%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse 90% 70% at 50% 0%, #000 30%, transparent 75%);
}

.bg-glow {
  position: fixed; inset: 0; z-index: -2; pointer-events: none;
  background:
    radial-gradient(600px 340px at 78% -4%, var(--glow-amber), transparent 70%),
    radial-gradient(700px 420px at 8% 12%, var(--glow-violet), transparent 70%);
}

.bg-noise {
  position: fixed; inset: 0; z-index: -1; pointer-events: none; opacity: var(--noise-opacity);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

/* ---------- top bar ---------- */

.topbar {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; gap: 28px;
  max-width: var(--max); margin: 0 auto; padding: 14px 24px;
  background: var(--topbar-bg);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line);
}

.brand {
  display: flex; align-items: center; gap: 10px;
  text-decoration: none; color: var(--paper);
  font-family: var(--serif); font-weight: 600; font-size: 19px; letter-spacing: 0.01em;
}

.brand img { display: block; }

.topnav { display: flex; gap: 22px; margin-left: auto; }

.topnav a {
  font-family: var(--mono); font-size: 12.5px; letter-spacing: 0.08em; text-transform: uppercase;
  color: var(--paper-dim); text-decoration: none; transition: color 0.2s;
}
.topnav a:hover { color: var(--amber); }

.domain {
  font-family: var(--mono); font-size: 12px; color: var(--paper-faint);
  border: 1px solid var(--line-strong); border-radius: 999px; padding: 4px 12px;
}

/* theme toggle */

.theme-toggle {
  display: inline-flex; align-items: center; justify-content: center;
  width: 34px; height: 34px; flex: none;
  background: transparent;
  border: 1px solid var(--line-strong);
  border-radius: 10px;
  color: var(--paper-dim);
  cursor: pointer;
  transition: color 0.2s, border-color 0.2s, background 0.2s;
}

.theme-toggle:hover { color: var(--amber); border-color: rgba(255, 178, 36, 0.5); background: var(--amber-soft); }

.theme-toggle svg { width: 17px; height: 17px; }

.theme-toggle .ic-sun { display: none; }
:root[data-theme="light"] .theme-toggle .ic-sun { display: block; }
:root[data-theme="light"] .theme-toggle .ic-moon { display: none; }

/* ---------- hero ---------- */

.hero {
  max-width: var(--max); margin: 0 auto;
  padding: 96px 24px 64px;
}

.hero-eyebrow {
  display: flex; align-items: center; gap: 10px;
  font-family: var(--mono); font-size: 12.5px; letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--paper-dim); margin-bottom: 26px;
}

.dot { width: 7px; height: 7px; border-radius: 50%; background: var(--amber); box-shadow: 0 0 12px var(--amber); }

.hero-title {
  font-family: var(--serif);
  font-size: clamp(44px, 7.2vw, 92px);
  font-weight: 560;
  line-height: 1.02;
  letter-spacing: -0.02em;
  max-width: 15ch;
}

.hero-title em {
  font-style: italic; font-weight: 430;
  color: var(--amber);
}

.hero-sub {
  margin-top: 26px; max-width: 56ch;
  font-size: 19px; line-height: 1.65; color: var(--paper-dim);
}

/* search */

.search-wrap {
  position: relative; max-width: 620px; margin-top: 40px;
}

.search-icon {
  position: absolute; left: 18px; top: 50%; transform: translateY(-50%);
  width: 19px; height: 19px; color: var(--paper-faint); pointer-events: none;
}

#search {
  width: 100%;
  background: var(--ink-2);
  border: 1px solid var(--line-strong);
  border-radius: 14px;
  padding: 16px 52px 16px 48px;
  color: var(--paper);
  font-family: var(--mono); font-size: 14.5px;
  outline: none;
  transition: border-color 0.25s, box-shadow 0.25s;
}
#search::placeholder { color: var(--paper-faint); }
#search:focus {
  border-color: var(--amber);
  box-shadow: 0 0 0 4px var(--amber-soft);
}

#search::-webkit-search-cancel-button { -webkit-appearance: none; }

.search-kbd {
  position: absolute; right: 16px; top: 50%; transform: translateY(-50%);
  font-family: var(--mono); font-size: 12px; color: var(--paper-faint);
  border: 1px solid var(--line-strong); border-bottom-width: 2px; border-radius: 6px;
  padding: 2px 8px; pointer-events: none;
}

/* stats */

.hero-stats {
  display: flex; gap: 48px; flex-wrap: wrap;
  margin-top: 52px; padding-top: 28px;
  border-top: 1px solid var(--line);
}

.hero-stats dt {
  font-family: var(--mono); font-size: 11px; letter-spacing: 0.16em; text-transform: uppercase;
  color: var(--paper-faint); margin-bottom: 4px;
}

.hero-stats dd {
  font-family: var(--serif); font-size: 34px; font-weight: 600; color: var(--paper);
  font-variant-numeric: tabular-nums;
}

/* ---------- section scaffolding ---------- */

main section { max-width: var(--max); margin: 0 auto; padding: 72px 24px; }

.section-title {
  font-family: var(--serif); font-size: clamp(30px, 3.6vw, 44px); font-weight: 560;
  letter-spacing: -0.01em;
}

.section-sub { margin-top: 10px; color: var(--paper-dim); font-size: 17.5px; max-width: 60ch; }

/* ---------- catalog ---------- */

.catalog-head {
  display: flex; align-items: center; gap: 20px; flex-wrap: wrap;
  margin-bottom: 36px;
}
.catalog-head .section-title { margin-right: auto; }

.chips { display: flex; gap: 8px; flex-wrap: wrap; }

.chip {
  display: inline-flex; align-items: center; gap: 8px;
  font-family: var(--mono); font-size: 12px; letter-spacing: 0.04em;
  color: var(--paper-dim);
  background: transparent;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  padding: 8px 14px;
  cursor: pointer;
  transition: color 0.2s, border-color 0.2s, background 0.2s;
}

.chip i { font-style: normal; font-size: 10px; color: var(--paper-faint); border: 1px solid var(--line-strong); border-radius: 4px; padding: 1px 5px; }

.chip:hover { color: var(--paper); border-color: var(--paper-faint); }

.chip.is-active {
  background: var(--amber); border-color: var(--amber); color: var(--ink);
  font-weight: 500;
}
.chip.is-active i { color: var(--ink); border-color: rgba(0, 0, 0, 0.3); }

.result-count {
  font-family: var(--mono); font-size: 12px; color: var(--paper-faint);
  font-variant-numeric: tabular-nums;
}

/* ---------- card grid ---------- */

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 20px;
}

.card {
  position: relative;
  display: flex; flex-direction: column;
  background: var(--ink-2);
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 26px 26px 22px;
  transition: transform 0.35s var(--ease), border-color 0.35s, box-shadow 0.35s, opacity 0.3s;
}

.card:hover {
  transform: translateY(-5px);
  border-color: rgba(255, 178, 36, 0.45);
  box-shadow: 0 18px 50px -18px rgba(0, 0, 0, 0.35), 0 0 0 1px rgba(255, 178, 36, 0.12);
}

.card.is-hidden { display: none; }

.card-top {
  display: flex; align-items: baseline; justify-content: space-between;
  margin-bottom: 18px;
}

.card-no {
  font-family: var(--serif); font-style: italic; font-weight: 340;
  font-size: 40px; line-height: 1; color: var(--amber);
}

.card-cat {
  font-family: var(--mono); font-size: 10.5px; letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--paper-faint);
  display: inline-flex; align-items: center; gap: 6px;
}
.card-cat i {
  font-style: normal; border: 1px solid var(--line-strong); border-radius: 4px; padding: 1px 5px;
}

.card-title {
  font-family: var(--serif); font-size: 25px; font-weight: 580; letter-spacing: -0.01em; line-height: 1.15;
}
.card-title a { color: var(--paper); text-decoration: none; }
.card-title a::after { content: ""; position: absolute; inset: 0; }
.card-title a:hover { color: var(--amber); }
.card:hover .card-title a { color: var(--amber); }

.card-tag {
  margin-top: 8px;
  font-style: italic; font-size: 16.5px; color: var(--paper-dim);
}

.card-desc {
  margin-top: 10px; font-size: 15.5px; line-height: 1.6; color: var(--paper-dim);
  flex-grow: 1;
}

.card-links {
  list-style: none; display: flex; flex-wrap: wrap; gap: 6px;
  margin-top: 18px;
}

.card-links a {
  position: relative; z-index: 1; /* sit above the stretched card link */
  display: inline-block;
  font-family: var(--mono); font-size: 11.5px; letter-spacing: 0.02em;
  color: var(--paper-dim); text-decoration: none;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  padding: 4px 11px;
  transition: color 0.2s, border-color 0.2s, background 0.2s;
}
.card-links a:hover {
  color: var(--amber); border-color: rgba(255, 178, 36, 0.5); background: var(--amber-soft);
}

.card-foot {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  margin-top: 20px; padding-top: 16px;
  border-top: 1px solid var(--line);
}

.card-meta {
  font-family: var(--mono); font-size: 11px; letter-spacing: 0.06em; text-transform: uppercase;
  color: var(--paper-faint); font-variant-numeric: tabular-nums;
}

.card-open {
  position: relative; z-index: 1;
  font-family: var(--mono); font-size: 12.5px;
  color: var(--amber); text-decoration: none; white-space: nowrap;
}
.card-open span { display: inline-block; transition: transform 0.25s var(--ease); }
.card-open:hover span { transform: translateX(4px); }

/* empty state */

.empty {
  margin-top: 28px; padding: 40px 24px; text-align: center;
  border: 1px dashed var(--line-strong); border-radius: 18px;
  color: var(--paper-dim); font-size: 17px;
}

.empty-clear {
  display: block; margin: 12px auto 0;
  font-family: var(--mono); font-size: 12.5px;
  color: var(--amber); background: none;
  border: 1px solid rgba(255, 178, 36, 0.4); border-radius: 999px;
  padding: 7px 16px; cursor: pointer;
}
.empty-clear:hover { background: var(--amber-soft); }

/* ---------- learning routes ---------- */

.routes { border-top: 1px solid var(--line); }

.route-list { list-style: none; margin-top: 40px; display: grid; gap: 16px; }

.route {
  background: var(--ink-2);
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 24px 28px;
  transition: border-color 0.3s, transform 0.35s var(--ease);
}
.route:hover { border-color: rgba(255, 178, 36, 0.35); transform: translateX(6px); }

.route-head {
  display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap;
  font-family: var(--mono); font-size: 11px; letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--paper-faint);
}
.route-no { color: var(--amber); }

.route-name {
  margin-top: 10px;
  font-family: var(--serif); font-size: 26px; font-weight: 570; letter-spacing: -0.01em;
}

.route-desc { margin-top: 6px; color: var(--paper-dim); font-size: 16px; max-width: 70ch; }

.route-path {
  display: flex; align-items: stretch; gap: 10px; flex-wrap: wrap;
  margin-top: 18px;
}

.route-path a {
  display: flex; align-items: baseline; gap: 9px;
  text-decoration: none;
  border: 1px solid var(--line-strong); border-radius: 12px;
  padding: 10px 16px;
  transition: border-color 0.2s, background 0.2s;
}
.route-path a:hover { border-color: rgba(255, 178, 36, 0.5); background: var(--amber-soft); }

.route-path b {
  font-family: var(--serif); font-style: italic; font-weight: 500; font-size: 19px;
  color: var(--amber);
}
.route-path i { font-family: var(--mono); font-style: normal; font-size: 12px; color: var(--paper-dim); }

.route-arrow { align-self: center; color: var(--paper-faint); font-family: var(--mono); }

/* ---------- about ---------- */

.about { border-top: 1px solid var(--line); }

.about-cols {
  margin-top: 28px;
  display: grid; grid-template-columns: 1fr 1fr; gap: 36px;
  color: var(--paper-dim); font-size: 17.5px; line-height: 1.7;
}

.about code {
  font-family: var(--mono); font-size: 0.86em;
  background: var(--ink-3); border: 1px solid var(--line);
  border-radius: 6px; padding: 1.5px 7px; color: var(--amber);
}

/* ---------- footer ---------- */

.footer {
  max-width: var(--max); margin: 40px auto 0; padding: 56px 24px 40px;
  border-top: 1px solid var(--line);
}

.footer-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 28px;
}

.footer-head {
  font-family: var(--mono); font-size: 11px; letter-spacing: 0.16em; text-transform: uppercase;
  color: var(--paper-faint); margin-bottom: 12px;
}

.footer-col a {
  display: block;
  color: var(--paper-dim); text-decoration: none;
  font-size: 15.5px; padding: 3px 0;
  transition: color 0.2s;
}
.footer-col a:hover { color: var(--amber); }

.footer-base {
  display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap;
  margin-top: 48px; padding-top: 20px;
  border-top: 1px solid var(--line);
  font-family: var(--mono); font-size: 12px; color: var(--paper-faint);
}

/* ---------- reveal animation ---------- */

.reveal {
  opacity: 0;
  transform: translateY(18px);
  animation: rise 0.7s var(--ease) forwards;
}
.grid .card:nth-child(1) { animation-delay: 0.05s; }
.grid .card:nth-child(2) { animation-delay: 0.10s; }
.grid .card:nth-child(3) { animation-delay: 0.15s; }
.grid .card:nth-child(4) { animation-delay: 0.20s; }
.grid .card:nth-child(5) { animation-delay: 0.25s; }
.grid .card:nth-child(6) { animation-delay: 0.30s; }
.grid .card:nth-child(7) { animation-delay: 0.35s; }
.grid .card:nth-child(8) { animation-delay: 0.40s; }
.grid .card:nth-child(9) { animation-delay: 0.45s; }
.route-list .route:nth-child(1) { animation-delay: 0.05s; }
.route-list .route:nth-child(2) { animation-delay: 0.12s; }
.route-list .route:nth-child(3) { animation-delay: 0.19s; }
.route-list .route:nth-child(4) { animation-delay: 0.26s; }

@keyframes rise {
  to { opacity: 1; transform: translateY(0); }
}

/* ---------- responsive ---------- */

@media (max-width: 760px) {
  .topnav { display: none; }
  .hero { padding: 64px 20px 48px; }
  main section { padding: 56px 20px; }
  .hero-stats { gap: 28px; }
  .about-cols { grid-template-columns: 1fr; }
  .grid { grid-template-columns: 1fr; }
  .card:hover, .route:hover { transform: none; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { animation: none; opacity: 1; transform: none; }
  .card, .route, .card-open span { transition: none; }
}