/* landing.css — shared styling for QUANTHEON Lab's static SEO pages (guides, tools,
   the /learn library, conversion landings). Premium + modern to match the app: ink/neon
   palette, layered gradient ("aurora") background, glass cards with neon glow, Inter type.
   Standalone (no build step). The generator content-hashes the URL (/landing.css?v=…),
   so edits here always bust the CDN cache. */
:root {
  --ink-950: #0b0f1a; --ink-900: #0f1424; --ink-800: #151b2e;
  --cyan: #22d3ee; --blue: #60a5fa; --violet: #a855f7; --green: #34d399; --amber: #fbbf24; --pink: #fb7185;
  --slate-100: #e2e8f0; --slate-200: #cbd5e1; --slate-300: #b6c2d4; --slate-400: #94a3b8; --slate-500: #64748b; --slate-600: #475569;
  --line: rgba(255, 255, 255, 0.08); --glass: rgba(255, 255, 255, 0.035);
  --grad: linear-gradient(100deg, var(--cyan), var(--blue), var(--violet));
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; min-height: 100vh; position: relative; color: var(--slate-300); background: var(--ink-950);
  font-family: "Inter", ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.65; -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility;
}

/* Ambient gradient background (fixed): layered neon glows + a soft aurora mesh + a faint,
   masked grid. Static (no animation) — rich but calm for reading and good for Core Web Vitals. */
.bg { position: fixed; inset: 0; z-index: -1; pointer-events: none; overflow: hidden;
  background:
    radial-gradient(900px 540px at 10% -10%, rgba(34, 211, 238, 0.16), transparent 60%),
    radial-gradient(820px 500px at 100% -6%, rgba(168, 85, 247, 0.15), transparent 58%),
    radial-gradient(760px 620px at 50% 118%, rgba(52, 211, 153, 0.10), transparent 60%),
    var(--ink-950);
}
.bg::before { content: ""; position: absolute; inset: -25%;
  background: conic-gradient(from 200deg at 60% 30%, rgba(34, 211, 238, 0.12), rgba(96, 165, 250, 0.10), rgba(168, 85, 247, 0.12), rgba(52, 211, 153, 0.08), rgba(34, 211, 238, 0.12));
  filter: blur(130px); opacity: 0.5;
}
.bg::after { content: ""; position: absolute; inset: 0;
  background-image: linear-gradient(rgba(255, 255, 255, 0.022) 1px, transparent 1px), linear-gradient(90deg, rgba(255, 255, 255, 0.022) 1px, transparent 1px);
  background-size: 52px 52px;
  -webkit-mask-image: radial-gradient(ellipse 85% 55% at 50% 0%, #000 35%, transparent 80%);
  mask-image: radial-gradient(ellipse 85% 55% at 50% 0%, #000 35%, transparent 80%);
}

.wrap { max-width: 880px; margin: 0 auto; padding: 0 24px; }
.wrap-wide { max-width: 1180px; }
a { color: var(--cyan); text-decoration: none; }
a:hover { text-decoration: underline; }
.grad { background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }

/* Header / footer */
.site-head { position: sticky; top: 0; z-index: 20; border-bottom: 1px solid var(--line); background: rgba(11, 15, 26, 0.6); backdrop-filter: blur(14px); -webkit-backdrop-filter: blur(14px); }
.site-foot { border-top: 1px solid var(--line); margin-top: 72px; }
.site-head .wrap, .site-foot .wrap { display: flex; align-items: center; gap: 16px; padding: 15px 24px; flex-wrap: wrap; max-width: 1180px; }
.brand { display: flex; align-items: center; gap: 7px; font-weight: 800; letter-spacing: -0.02em; font-size: 18px; color: var(--slate-100); }
.brand .q { background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.brand .dot { color: var(--green); font-size: 11px; }
.nav { margin-left: auto; display: flex; gap: 20px; font-size: 14px; font-weight: 600; flex-wrap: wrap; }
.nav a { color: var(--slate-400); }
.nav a:hover { color: var(--cyan); text-decoration: none; }
.site-foot .wrap { color: var(--slate-500); font-size: 13px; }

/* Hero / headings */
.eyebrow { display: inline-block; text-transform: uppercase; letter-spacing: 0.2em; font-weight: 700; font-size: 12.5px; color: var(--violet); padding: 6px 13px; border: 1px solid var(--line); border-radius: 999px; background: var(--glass); }
h1 { color: var(--slate-100); font-size: clamp(34px, 5.2vw, 52px); line-height: 1.05; letter-spacing: -0.025em; font-weight: 800; margin: 20px 0 16px; }
h2 { color: var(--slate-100); font-size: clamp(23px, 3vw, 30px); letter-spacing: -0.01em; font-weight: 800; margin: 50px 0 14px; }
h3 { color: var(--slate-100); font-size: 18.5px; font-weight: 700; margin: 28px 0 8px; }
.lead { font-size: 20px; line-height: 1.6; color: var(--slate-200); max-width: 730px; }
main { padding: 56px 0 24px; }
p, li { font-size: 16.5px; }
li { margin-bottom: 6px; }
strong { color: var(--slate-100); }
em { color: var(--slate-200); }
hr { border: 0; border-top: 1px solid var(--line); margin: 48px 0; }
.muted { color: var(--slate-500); font-size: 13px; }

/* Cards / callouts */
.card { background: var(--glass); border: 1px solid var(--line); border-radius: 18px; padding: 24px; backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px); }
.grid { display: grid; gap: 16px; }
@media (min-width: 640px) { .grid.cols-2 { grid-template-columns: 1fr 1fr; } }

/* Buttons */
.btn { display: inline-flex; align-items: center; gap: 8px; font-weight: 700; font-size: 15px; border-radius: 13px; padding: 13px 22px; cursor: pointer; border: 1px solid transparent; transition: transform 0.15s ease, box-shadow 0.15s ease, filter 0.15s ease; }
.btn-primary { color: #04121a; background: var(--grad); box-shadow: 0 10px 32px -12px rgba(34, 211, 238, 0.55); }
.btn-primary:hover { text-decoration: none; transform: translateY(-1px); filter: brightness(1.06); box-shadow: 0 14px 40px -12px rgba(34, 211, 238, 0.65); }
.btn-ghost { color: var(--slate-100); background: var(--glass); border-color: var(--line); }
.btn-ghost:hover { text-decoration: none; border-color: rgba(34, 211, 238, 0.4); color: #fff; }
.cta { margin-top: 30px; display: flex; gap: 12px; flex-wrap: wrap; }

/* Calculator widgets */
.calc { margin: 30px 0; }
.calc label { display: block; font-size: 13px; font-weight: 600; color: var(--slate-400); margin-bottom: 7px; }
.calc .row { margin-bottom: 18px; }
.calc input {
  width: 100%; background: rgba(8, 11, 20, 0.7); border: 1px solid var(--line); border-radius: 11px;
  color: var(--slate-100); font-size: 16px; padding: 12px 14px; font-variant-numeric: tabular-nums;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
.calc input:focus { outline: none; border-color: rgba(34, 211, 238, 0.55); box-shadow: 0 0 0 3px rgba(34, 211, 238, 0.12); }
.result { margin-top: 10px; display: flex; align-items: baseline; gap: 12px; flex-wrap: wrap; }
.result .big { font-size: 42px; font-weight: 800; background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; font-variant-numeric: tabular-nums; letter-spacing: -0.01em; }
.result .verdict { font-weight: 700; }
.v-good { color: var(--green); }
.v-mid { color: var(--amber); }
.v-bad { color: var(--pink); }

/* FAQ */
.faq details { border: 1px solid var(--line); border-radius: 13px; padding: 4px 18px; margin-bottom: 11px; background: var(--glass); transition: border-color 0.15s ease; }
.faq details[open] { border-color: rgba(34, 211, 238, 0.25); }
.faq summary { cursor: pointer; font-weight: 700; color: var(--slate-100); padding: 13px 0; list-style: none; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::before { content: "+"; color: var(--cyan); font-weight: 800; display: inline-block; width: 18px; }
.faq details[open] summary::before { content: "–"; }
.faq p { margin: 0 0 15px; }

/* Library / hub cards (/learn, /guides, /tools) */
.lib-section-title { display: flex; align-items: center; gap: 12px; color: var(--slate-200); font-size: 12.5px; font-weight: 800; text-transform: uppercase; letter-spacing: 0.2em; margin: 46px 0 18px; }
.lib-section-title::after { content: ""; flex: 1; height: 1px; background: linear-gradient(90deg, var(--line), transparent); }
.lib-grid { display: grid; gap: 16px; grid-template-columns: 1fr; }
@media (min-width: 560px) { .lib-grid { grid-template-columns: repeat(auto-fill, minmax(310px, 1fr)); } }
.lib-card {
  position: relative; display: flex; gap: 15px; align-items: flex-start; padding: 20px;
  border: 1px solid var(--line); border-radius: 18px; background: var(--glass);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}
.lib-card:hover {
  transform: translateY(-4px); text-decoration: none;
  background: rgba(255, 255, 255, 0.05);
  border-color: color-mix(in srgb, var(--ic, var(--cyan)) 50%, transparent);
  box-shadow: 0 18px 50px -18px color-mix(in srgb, var(--ic, var(--cyan)) 60%, transparent);
}
.lib-ico {
  flex: 0 0 auto; width: 46px; height: 46px; display: grid; place-items: center; border-radius: 13px;
  color: var(--ic, var(--cyan));
  background: linear-gradient(150deg, color-mix(in srgb, var(--ic, var(--cyan)) 22%, transparent), color-mix(in srgb, var(--ic, var(--cyan)) 7%, transparent));
  border: 1px solid color-mix(in srgb, var(--ic, var(--cyan)) 34%, transparent);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.08);
}
.lib-ico svg { width: 22px; height: 22px; }
.lib-card-body { display: flex; flex-direction: column; gap: 5px; min-width: 0; }
.lib-card-title { color: var(--slate-100); font-weight: 700; font-size: 16.5px; }
.lib-card-desc { color: var(--slate-400); font-size: 14px; line-height: 1.55; }
.lib-card-meta { color: var(--slate-500); font-size: 11.5px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.07em; margin-top: 3px; }