/* LU AI Limited — site styles. Plain CSS, light and dark, no JavaScript. */
:root {
  --bg: #f6f7f9;
  --surface: #ffffff;
  --ink: #101828;
  --muted: #566074;
  --line: #e3e6ec;
  --brand: #1b2a49;
  --brand-ink: #ffffff;
  --link: #1d4ed8;
  --accent: #1b2a49; /* per-app colour overrides this via .app-<slug> */
  --radius: 16px;
  --shadow: 0 1px 2px rgba(16, 24, 40, 0.06), 0 10px 28px rgba(16, 24, 40, 0.07);
  --font: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1220;
    --surface: #151c2e;
    --ink: #eef1f7;
    --muted: #a3adc2;
    --line: #27314a;
    --brand: #e8ecf7;
    --brand-ink: #0d1220;
    --link: #8fb0ff;
    --shadow: none;
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
h1, h2, h3 { line-height: 1.2; letter-spacing: -0.015em; margin: 0 0 0.6em; }
h1 { font-size: clamp(2rem, 5vw, 3.1rem); font-weight: 750; }
h2 { font-size: 1.55rem; font-weight: 700; margin-top: 1.8em; }
h3 { font-size: 1.2rem; font-weight: 650; }
p { margin: 0 0 1em; }
a { color: var(--link); text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }
a:focus-visible, .btn:focus-visible, summary:focus-visible {
  outline: 3px solid var(--link);
  outline-offset: 3px;
  border-radius: 6px;
}
.muted { color: var(--muted); }
.small { font-size: 0.9rem; }
.plain { list-style: none; margin: 0; padding: 0; }
.plain li { margin: 0.35em 0; }

.wrap { width: min(1080px, 100% - 2.5rem); margin-inline: auto; }
.narrow { width: min(1080px, 100% - 2.5rem); margin-inline: auto; }
.narrow > * { max-width: 760px; }

.skip {
  position: absolute; left: -999px; top: 0; background: var(--brand); color: var(--brand-ink);
  padding: 0.6rem 1rem; z-index: 10; border-radius: 0 0 8px 0;
}
.skip:focus { left: 0; }

/* header */
.site-header {
  position: sticky; top: 0; z-index: 5;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(160%) blur(10px);
  border-bottom: 1px solid var(--line);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: 0.75rem 0; flex-wrap: wrap; }
.brand { display: inline-flex; align-items: center; gap: 0.65rem; text-decoration: none; color: var(--ink); font-weight: 700; }
.brand-mark {
  display: inline-grid; place-items: center; width: 2.2rem; height: 2.2rem; border-radius: 0.6rem;
  background: var(--brand); color: var(--brand-ink); font-size: 0.95rem; letter-spacing: 0.02em;
}
nav { display: flex; gap: 1.4rem; flex-wrap: wrap; }
nav a { color: var(--muted); text-decoration: none; font-weight: 550; font-size: 0.97rem; }
nav a:hover { color: var(--ink); }

/* hero */
.hero { padding: clamp(3.5rem, 9vw, 6.5rem) 0 clamp(3rem, 7vw, 5rem); }
.hero .wrap > * { max-width: 860px; }
.eyebrow { font-size: 0.85rem; font-weight: 650; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); margin-bottom: 1rem; display: flex; gap: 0.6rem; align-items: center; flex-wrap: wrap; }
.lead { font-size: clamp(1.1rem, 2.2vw, 1.3rem); color: var(--muted); max-width: 40em; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 0.75rem; margin-top: 1.6rem; }

.btn {
  display: inline-block; padding: 0.8rem 1.35rem; border-radius: 999px;
  background: var(--brand); color: var(--brand-ink); text-decoration: none; font-weight: 650;
  border: 2px solid var(--brand);
}
.btn:hover { opacity: 0.9; }
.btn-ghost { background: transparent; color: var(--ink); border-color: var(--line); }
.btn-ghost:hover { border-color: var(--ink); opacity: 1; }

/* sections */
.section { padding: clamp(2.5rem, 6vw, 4.5rem) 0; }
.section-alt { background: var(--surface); border-block: 1px solid var(--line); }
.section h2:first-child { margin-top: 0; }
.section-lead { color: var(--muted); max-width: 42em; margin-bottom: 2rem; }

/* app cards */
.app-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(290px, 1fr)); gap: 1.25rem; }
.app-card {
  position: relative; display: flex; flex-direction: column; gap: 1rem; padding: 1.6rem 1.5rem 1.4rem;
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow); color: var(--ink); text-decoration: none; overflow: hidden;
  transition: transform 0.15s ease, border-color 0.15s ease;
}
.app-card::before { content: ''; position: absolute; inset: 0 0 auto 0; height: 5px; background: var(--accent); }
.app-card:hover { transform: translateY(-3px); border-color: var(--accent); }
.app-mark {
  display: inline-grid; place-items: center; width: 3.2rem; height: 3.2rem; border-radius: 0.9rem;
  background: var(--accent); color: #fff; font-weight: 750; font-size: 1.1rem; letter-spacing: 0.02em; flex: none;
}
.app-mark-lg { width: 5rem; height: 5rem; border-radius: 1.3rem; font-size: 1.6rem; }
.app-card-top { display: flex; justify-content: space-between; align-items: flex-start; gap: 1rem; }
.app-card-body { display: flex; flex-direction: column; gap: 0.4rem; flex: 1; }
.app-card-title { font-size: 1.25rem; font-weight: 700; }
.app-card-text { color: var(--muted); font-size: 0.98rem; line-height: 1.55; }
.card-link { font-weight: 650; color: var(--accent); font-size: 0.95rem; }
@media (prefers-color-scheme: dark) { .card-link { color: var(--ink); } }

.pill {
  display: inline-block; font-size: 0.72rem; font-weight: 700; letter-spacing: 0.05em; text-transform: uppercase;
  padding: 0.2rem 0.6rem; border-radius: 999px; border: 1px solid var(--line); color: var(--muted); background: transparent;
}
.pill-live { color: #0f6b3a; border-color: #0f6b3a; }
.pill-beta { color: #92560a; border-color: #92560a; }
@media (prefers-color-scheme: dark) { .pill-live { color: #6ee7a8; border-color: #6ee7a8; } .pill-beta { color: #fbbf5a; border-color: #fbbf5a; } }

/* app page */
.app-hero { padding: clamp(2.5rem, 6vw, 4.5rem) 0 1.5rem; border-bottom: 1px solid var(--line); background: linear-gradient(180deg, color-mix(in srgb, var(--accent) 9%, var(--bg)), var(--bg)); }
.app-hero-inner { display: flex; gap: 1.75rem; align-items: center; flex-wrap: wrap; }
.app-hero h1 { margin-bottom: 0.3em; }
.feature-list { padding-left: 0; list-style: none; display: grid; gap: 0.75rem; }
.feature-list li { position: relative; padding-left: 1.9rem; }
.feature-list li::before {
  content: ''; position: absolute; left: 0; top: 0.5em; width: 1rem; height: 1rem; border-radius: 50%;
  background: var(--accent); opacity: 0.9;
}
.link-list { padding-left: 1.2rem; }
.link-list li { margin: 0.4em 0; }

/* legal / prose pages */
.prose h1 { margin-bottom: 0.4em; }
.prose h2 { font-size: 1.3rem; margin-top: 2em; }
.prose h3 { font-size: 1.1rem; margin-top: 1.5em; }
.prose ul, .prose ol { padding-left: 1.4rem; }
.prose li { margin: 0.35em 0; }
.prose table { width: 100%; border-collapse: collapse; margin: 1.2em 0; font-size: 0.95rem; display: block; overflow-x: auto; }
.prose th, .prose td { border: 1px solid var(--line); padding: 0.55rem 0.75rem; text-align: left; vertical-align: top; }
.prose th { background: color-mix(in srgb, var(--ink) 5%, transparent); }
.prose blockquote { margin: 1.2em 0; padding: 0.2em 1.1em; border-left: 4px solid var(--line); color: var(--muted); }
.prose code { background: color-mix(in srgb, var(--ink) 8%, transparent); padding: 0.1em 0.4em; border-radius: 6px; font-size: 0.92em; }
.crumb { font-size: 0.95rem; margin-bottom: 1.2rem; }
.banner {
  border: 1px solid #b45309; background: color-mix(in srgb, #f59e0b 14%, var(--surface)); color: var(--ink);
  border-radius: 12px; padding: 0.85rem 1.1rem; margin: 0 0 1.6rem; font-size: 0.97rem;
}
.contact-box { font-size: 1.25rem; font-weight: 650; padding: 1rem 1.25rem; background: var(--surface); border: 1px solid var(--line); border-radius: 12px; display: inline-block; }
.contact-list { padding-left: 1.2rem; }
details { border: 1px solid var(--line); border-radius: 12px; background: var(--surface); padding: 0.2rem 1rem; margin: 0.6rem 0; }
summary { cursor: pointer; font-weight: 650; padding: 0.7rem 0; }
details p { color: var(--muted); }

/* footer */
.site-footer { border-top: 1px solid var(--line); padding: 3rem 0 2rem; margin-top: 2rem; background: var(--surface); }
.footer-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: 2rem; margin-bottom: 2rem; }
.footer-brand { font-weight: 750; font-size: 1.1rem; margin-bottom: 0.3rem; }
.footer-heading { font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.08em; color: var(--muted); margin: 0 0 0.8rem; font-weight: 700; }
.site-footer a { color: var(--ink); text-decoration: none; }
.site-footer a:hover { text-decoration: underline; }

@media (max-width: 560px) {
  body { font-size: 16px; }
  nav { gap: 1rem; }
  .brand-name { font-size: 0.98rem; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .app-card { transition: none; }
}