/* Erdos-FAI — marketing site
   Light, premium design system shared with Erdos FC: warm-white paper,
   oversized tight-tracked display type, ink-black UI, blue→violet→teal
   signature gradient, dark code/terminal panels floated on white. */

:root {
  --bg: #ffffff;
  --paper: #f6f5f1;
  --paper-2: #efeee9;
  --ink: #0a0b0d;
  --ink-2: #3c3f47;
  --muted: #6c707a;
  --line: rgba(10, 11, 13, 0.10);
  --line-2: rgba(10, 11, 13, 0.06);
  --code: #0c0e16;
  --code-ink: #cdd6e6;

  --g1: #2f5bff;   /* blue   */
  --g2: #7b5cff;   /* violet */
  --g3: #16c8b0;   /* teal   */

  /* semantic (lifecycle / status) — tuned for light backgrounds */
  --blue: #2f5bff;
  --red: #e2483d;
  --green: #0f9e6e;
  --amber: #c4821a;

  --radius: 18px;
  --maxw: 1240px;
  --shadow: 0 1px 2px rgba(10,11,13,.04), 0 20px 54px -30px rgba(10,11,13,.32);
  --display: "Space Grotesk", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, monospace;
}

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

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--ink);
  line-height: 1.6;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}
::selection { background: rgba(47, 91, 255, 0.18); }

/* soft light wash behind the hero (was a dark blueprint grid) */
.grid-bg {
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(680px 360px at 80% -6%, rgba(123, 92, 255, 0.14), transparent 62%),
    radial-gradient(600px 360px at 4% 2%, rgba(47, 91, 255, 0.10), transparent 60%),
    radial-gradient(460px 320px at 60% 26%, rgba(22, 200, 176, 0.08), transparent 64%);
  mask-image: linear-gradient(180deg, #000 0%, #000 46%, transparent 72%);
}

a { color: inherit; text-decoration: none; }
b { color: var(--ink); font-weight: 600; }
em { font-style: italic; }
h1, h2, h3, h4, .brand { font-family: var(--display); }

/* ---------- layout primitives ---------- */
section { padding: clamp(72px, 9vw, 116px) clamp(20px, 6vw, 96px); max-width: var(--maxw); margin: 0 auto; }
.section-kicker {
  display: inline-block;
  font-family: var(--font);
  font-size: 13px; letter-spacing: 0.14em; text-transform: uppercase; font-weight: 600;
  color: var(--g1);
  margin-bottom: 14px;
}
h2 { font-size: clamp(28px, 4vw, 46px); font-weight: 600; letter-spacing: -0.03em; line-height: 1.05; }
.section-sub { color: var(--ink-2); max-width: 640px; margin-top: 18px; font-size: clamp(16px, 1.6vw, 18px); }

.accent {
  background: linear-gradient(108deg, var(--g1), var(--g2) 55%, var(--g3));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}

/* ---------- buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 21px; border-radius: 999px;
  font-family: var(--font); font-weight: 600; font-size: 15px;
  border: 1px solid transparent; cursor: pointer; transition: .18s ease;
}
.btn-primary { background: var(--ink); color: #fff; }
.btn-primary:hover { background: #23262e; transform: translateY(-1px); box-shadow: 0 12px 24px -10px rgba(10,11,13,.5); }
.btn-ghost { border-color: var(--line); color: var(--ink); background: #fff; }
.btn-ghost:hover { border-color: var(--ink); background: var(--paper); }

/* ---------- nav ---------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; justify-content: space-between;
  padding: 16px clamp(20px, 6vw, 96px);
  max-width: var(--maxw); margin: 0 auto;
  backdrop-filter: saturate(180%) blur(14px);
  background: rgba(255, 255, 255, 0.72);
  border-bottom: 1px solid var(--line-2);
}
.brand { display: flex; align-items: center; gap: 11px; font-size: 19px; font-weight: 600; letter-spacing: -0.02em; }
.brand b { font-weight: 700; }
.brand-mark { position: relative; overflow: hidden; width: 30px; height: 30px; border-radius: 9px;
  background: conic-gradient(from 210deg, var(--g1), var(--g3), var(--g2), var(--g1)); }
.brand-mark::after { content: ""; position: absolute; inset: 6px; border-radius: 5px; background: #fff; }
.nav-links { display: flex; align-items: center; gap: 28px; font-size: 15px; color: var(--ink-2); font-weight: 500; }
.nav-links a:not(.btn):hover { color: var(--ink); }
.nav-links a.active { color: var(--ink); }

/* ---------- hero ---------- */
.hero {
  display: grid; grid-template-columns: 1.05fr 0.95fr; gap: 56px; align-items: center;
  padding-top: 60px; padding-bottom: 56px;
}
.eyebrow { font-family: var(--font); font-size: 13px; letter-spacing: 0.04em; text-transform: none; color: var(--ink-2); font-weight: 600; margin-bottom: 20px;
  display: inline-flex; align-items: center; gap: 9px; background: #fff; border: 1px solid var(--line); padding: 7px 14px; border-radius: 999px; box-shadow: var(--shadow); }
.hero h1 { font-size: clamp(38px, 5.8vw, 70px); font-weight: 600; line-height: 1.02; letter-spacing: -0.035em; }
.lede { color: var(--ink-2); font-size: clamp(17px, 2vw, 20px); max-width: 560px; margin-top: 24px; line-height: 1.55; }
.hero-cta { display: flex; gap: 13px; margin-top: 32px; flex-wrap: wrap; }
.badges { display: flex; gap: 9px; flex-wrap: wrap; list-style: none; margin-top: 28px; }
.badges li { font-family: var(--font); font-size: 13px; font-weight: 500; color: var(--ink-2); padding: 6px 13px; border: 1px solid var(--line); border-radius: 999px; background: #fff; }

/* terminal — dark panel on white */
.hero-panel { perspective: 1200px; }
.terminal {
  background: var(--code);
  border: 1px solid rgba(255,255,255,0.08); border-radius: var(--radius);
  box-shadow: 0 40px 90px -36px rgba(10,11,13,0.55);
  overflow: hidden;
}
.term-bar { display: flex; align-items: center; gap: 7px; padding: 13px 16px; border-bottom: 1px solid rgba(255,255,255,0.07); }
.term-bar span { width: 11px; height: 11px; border-radius: 50%; background: #36405a; }
.term-bar span:nth-child(1){ background:#ff5f57; } .term-bar span:nth-child(2){ background:#febc2e; } .term-bar span:nth-child(3){ background:#28c840; }
.term-bar em { margin-left: 10px; font-family: var(--mono); font-style: normal; font-size: 12px; color: #8a93ad; }
.term-body { font-family: var(--mono); font-size: 12.6px; line-height: 1.7; padding: 18px 20px; color: var(--code-ink); white-space: pre-wrap; }
.c-dim { color: #7b85a3; } .c-ok { color: #5fe3c8; } .c-warn { color: #ffc46b; }

/* ---------- lifecycle ---------- */
.lifecycle { border-top: 1px solid var(--line-2); }
.stages { display: grid; grid-template-columns: repeat(5, 1fr); gap: 14px; margin-top: 44px; }
.stage { position: relative; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 24px 20px; transition: .2s ease; }
.stage:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.stage-no { font-family: var(--mono); font-size: 12px; color: var(--muted); }
.stage h3 { margin: 8px 0 8px; font-size: 19px; font-weight: 600; }
.stage p { color: var(--ink-2); font-size: 13.5px; }
.stage-tag { position: absolute; top: 18px; right: 16px; font-family: var(--mono); font-size: 10px; letter-spacing: .08em; padding: 3px 7px; border-radius: 5px; }
.tag-blue { color: var(--blue); background: rgba(47,91,255,0.10); }
.tag-red { color: var(--red); background: rgba(226,72,61,0.10); }
.tag-green { color: var(--green); background: rgba(15,158,110,0.10); }

/* ---------- layers ---------- */
.layers { background: var(--paper); max-width: none; border-top: 1px solid var(--line-2); border-bottom: 1px solid var(--line-2); }
.layers > * { max-width: var(--maxw); margin-left: auto; margin-right: auto; }
.layer-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin-top: 44px; }
.layer { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 28px 26px; transition: .22s ease; }
.layer:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.layer-head { display: flex; align-items: baseline; gap: 12px; margin-bottom: 12px; }
.layer-no { font-family: var(--mono); font-size: 24px; font-weight: 600;
  background: linear-gradient(120deg, var(--g1), var(--g2)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.layer-head h3 { font-size: 20px; font-weight: 600; letter-spacing: -0.01em; }
.layer p { color: var(--ink-2); font-size: 15px; }
.layer-code { display: inline-block; margin-top: 18px; font-family: var(--mono); font-size: 12.5px; color: var(--g1); background: rgba(47,91,255,0.07); border: 1px solid var(--line-2); padding: 5px 10px; border-radius: 7px; }
.layer-cta { display: flex; flex-direction: column; justify-content: center; gap: 14px;
  background: var(--ink); border-color: var(--ink); color: #fff; position: relative; overflow: hidden; }
.layer-cta::before { content: ""; position: absolute; inset: 0;
  background: radial-gradient(420px 240px at 18% 0%, rgba(123,92,255,.32), transparent 60%),
              radial-gradient(360px 240px at 100% 110%, rgba(22,200,176,.22), transparent 60%); }
.layer-cta > * { position: relative; }
.layer-cta h3 { font-size: 26px; font-weight: 600; letter-spacing: -0.02em; line-height: 1.1; color: #fff; }
.layer-cta p { color: rgba(255,255,255,0.72); }
.layer-cta .btn-primary { background: #fff; color: var(--ink); align-self: flex-start; }
.layer-cta .btn-primary:hover { background: #f0f0f0; }

/* ---------- architecture ---------- */
.arch-diagram { margin-top: 40px; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 26px; box-shadow: var(--shadow); }
.arch-diagram svg { width: 100%; height: auto; }
.a-outer-rect { fill: rgba(226,72,61,0.04); stroke: rgba(226,72,61,0.45); stroke-width: 1.2; }
.a-mid-rect { fill: rgba(15,158,110,0.04); stroke: rgba(15,158,110,0.40); stroke-width: 1.2; }
.a-inner-rect { fill: rgba(47,91,255,0.05); stroke: rgba(47,91,255,0.45); stroke-width: 1.2; }
.a-label { fill: var(--red); font-family: var(--mono); font-size: 12px; }
.a-label-dim { fill: var(--muted); font-family: var(--mono); font-size: 12px; }
.a-agent rect { fill: #fff; stroke: var(--g1); stroke-width: 1.3; }
.a-agent text { fill: var(--ink); font-family: var(--mono); font-size: 13px; text-anchor: middle; }
.a-flow { stroke: var(--g1); stroke-width: 1.6; marker-end: url(#arrow); opacity: 0.8; }
.a-loop { fill: var(--green); font-family: var(--mono); font-size: 12px; text-anchor: middle; }

/* ---------- get started ---------- */
.start-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; margin-top: 44px; }
.start-step h4 { font-family: var(--font); font-size: 14px; font-weight: 600; color: var(--ink); margin-bottom: 12px; }
.code-block { position: relative; background: var(--code); border: 1px solid rgba(255,255,255,0.08); border-radius: var(--radius); overflow: hidden; box-shadow: 0 30px 70px -34px rgba(10,11,13,0.5); }
.code-block pre { padding: 20px; overflow-x: auto; }
.code-block code { font-family: var(--mono); font-size: 13px; line-height: 1.75; color: var(--code-ink); }
.copy { position: absolute; top: 11px; right: 11px; font-family: var(--mono); font-size: 11px; color: #8a93ad; background: rgba(255,255,255,0.06); border: 1px solid rgba(255,255,255,0.12); border-radius: 7px; padding: 5px 10px; cursor: pointer; transition: .15s; }
.copy:hover { color: #fff; border-color: rgba(255,255,255,0.4); }
.c-dim { color: #7b85a3; } .c-key { color: #7aa2ff; } .c-str { color: #5fe3c8; }
.start-note { margin-top: 22px; color: var(--ink-2); font-size: 14.5px; }
.start-note code { font-family: var(--mono); font-size: 12.5px; color: var(--g1); background: rgba(47,91,255,0.07); border: 1px solid var(--line-2); padding: 2px 7px; border-radius: 6px; }

/* ---------- suite ---------- */
.suite-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; margin-top: 44px; }
.suite-card { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 26px 22px; transition: .2s; }
.suite-card:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.suite-card h3 { font-size: 18px; margin-bottom: 8px; font-weight: 600; }
.suite-card p { color: var(--ink-2); font-size: 14px; }

/* ---------- footer ---------- */
.footer { border-top: 1px solid var(--line-2); padding: 56px clamp(20px, 6vw, 96px) 44px; max-width: var(--maxw); margin: 0 auto; display: grid; grid-template-columns: 2fr 1fr; gap: 24px; align-items: start; }
.footer-brand span { font-size: 19px; font-weight: 600; font-family: var(--display); } .footer-brand b { font-weight: 700; }
.footer-brand p { color: var(--ink-2); font-size: 14.5px; max-width: 440px; margin-top: 12px; }
.footer-links { display: flex; flex-direction: column; gap: 9px; color: var(--ink-2); font-weight: 500; }
.footer-links a:hover { color: var(--g1); }
.footer-fine { grid-column: 1 / -1; color: var(--muted); font-size: 12.5px; border-top: 1px solid var(--line-2); padding-top: 22px; margin-top: 12px; }

/* ---------- reveal animation ---------- */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity .6s ease, transform .6s ease; }
.reveal.in { opacity: 1; transform: none; }

/* ---------- responsive ---------- */
@media (max-width: 960px) {
  .hero { grid-template-columns: 1fr; }
  .stages { grid-template-columns: repeat(2, 1fr); }
  .layer-grid { grid-template-columns: 1fr 1fr; }
  .suite-grid { grid-template-columns: 1fr 1fr; }
  .start-grid { grid-template-columns: 1fr; }
  .footer { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  .nav-links a:not(.btn-ghost) { display: none; }
  .stages, .layer-grid, .suite-grid { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) { * { animation: none !important; } .reveal { opacity: 1; transform: none; } }