/* os.ling-lang.org — design system
   Base identity from ling-lang.org (near-black + white, monospace accents)
   and ling-lin.me (teal/cyan accent on "灵"), pushed toward an Apple
   Store / Adobe-product level of gloss and color per the brief: big
   gradient hero, glassy cards, saturated feature-tile colors, generous
   whitespace, large confident type. */

:root {
  --bg: #07070c;
  --bg-elevated: #101018;
  --bg-card: rgba(255, 255, 255, 0.04);
  --border: rgba(255, 255, 255, 0.09);
  --text: #f4f4f8;
  --text-dim: #9a9aab;
  --text-faint: #62626f;

  --teal: #2dd4bf;
  --cyan: #22d3ee;
  --purple: #a78bfa;
  --pink: #f472b6;
  --orange: #fb923c;
  --blue: #60a5fa;
  --green: #4ade80;

  --gradient-hero: radial-gradient(circle at 15% 20%, rgba(45, 212, 191, 0.35), transparent 40%),
    radial-gradient(circle at 85% 15%, rgba(167, 139, 250, 0.30), transparent 45%),
    radial-gradient(circle at 60% 80%, rgba(244, 114, 182, 0.25), transparent 45%),
    radial-gradient(circle at 30% 90%, rgba(251, 146, 60, 0.20), transparent 40%),
    #07070c;

  --gradient-text: linear-gradient(90deg, var(--teal), var(--cyan), var(--purple), var(--pink));

  --radius: 20px;
  --radius-sm: 12px;
  --shadow-soft: 0 20px 60px -20px rgba(0, 0, 0, 0.6);
  --shadow-glow-teal: 0 0 40px -10px rgba(45, 212, 191, 0.5);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, "SF Pro Display", "Segoe UI", "Inter", ui-sans-serif, system-ui, sans-serif;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

code, pre, .mono {
  font-family: "SF Mono", "Cascadia Code", "JetBrains Mono", Consolas, monospace;
}

a { color: inherit; text-decoration: none; }

img { max-width: 100%; display: block; }

.container {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 32px;
}

/* ─── Nav ──────────────────────────────────────────────────────────────── */

.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(20px) saturate(160%);
  -webkit-backdrop-filter: blur(20px) saturate(160%);
  background: rgba(7, 7, 12, 0.72);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: 1180px;
  margin: 0 auto;
  padding: 16px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.1rem;
  letter-spacing: -0.01em;
}

.brand .glyph {
  font-size: 1.35rem;
  color: var(--purple);
}

.nav-links {
  display: flex;
  gap: 28px;
  align-items: center;
  font-size: 0.95rem;
  color: var(--text-dim);
}

.nav-links a { transition: color 0.15s ease; }
.nav-links a:hover { color: var(--text); }

.nav-cta {
  background: var(--gradient-text);
  color: #07070c !important;
  font-weight: 600;
  padding: 9px 18px;
  border-radius: 999px;
  font-size: 0.9rem;
}

/* ─── Hero ─────────────────────────────────────────────────────────────── */

.hero {
  background: var(--gradient-hero);
  padding: 120px 32px 100px;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero-eyebrow {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--teal);
  background: rgba(45, 212, 191, 0.12);
  border: 1px solid rgba(45, 212, 191, 0.3);
  padding: 6px 16px;
  border-radius: 999px;
  margin-bottom: 28px;
}

.hero h1 {
  font-size: clamp(2.8rem, 6vw, 5rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  margin: 0 0 20px;
  line-height: 1.05;
}

.hero h1 .accent {
  color: var(--purple);
}

.hero p.lede {
  font-size: 1.25rem;
  color: var(--text-dim);
  max-width: 640px;
  margin: 0 auto 44px;
}

.hero-actions {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 15px 30px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 1rem;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
  border: 1px solid transparent;
}

.btn:hover { transform: translateY(-2px); }

.btn-primary {
  background: var(--gradient-text);
  color: #07070c;
  box-shadow: var(--shadow-glow-teal);
}

.btn-secondary {
  background: var(--bg-card);
  border-color: var(--border);
  color: var(--text);
  backdrop-filter: blur(10px);
}

.btn-secondary:hover { border-color: rgba(255, 255, 255, 0.25); }

/* ─── Sections ─────────────────────────────────────────────────────────── */

section { padding: 96px 0; }

.section-head { text-align: center; max-width: 640px; margin: 0 auto 64px; }

.section-eyebrow {
  color: var(--purple);
  font-weight: 600;
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 12px;
}

.section-head h2 {
  font-size: clamp(2rem, 4vw, 2.75rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin: 0 0 16px;
}

.section-head p { color: var(--text-dim); font-size: 1.1rem; margin: 0; }

/* ─── Feature grid (colorful tiles, Apple-Store-card style) ──────────────── */

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  backdrop-filter: blur(10px);
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.card:hover {
  transform: translateY(-4px);
  border-color: rgba(255, 255, 255, 0.18);
  box-shadow: var(--shadow-soft);
}

.tile-icon {
  width: 52px;
  height: 52px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  margin-bottom: 20px;
}

.tile-icon.teal   { background: linear-gradient(135deg, var(--teal), #0d9488); }
.tile-icon.purple { background: linear-gradient(135deg, var(--purple), #7c3aed); }
.tile-icon.pink   { background: linear-gradient(135deg, var(--pink), #db2777); }
.tile-icon.orange { background: linear-gradient(135deg, var(--orange), #ea580c); }
.tile-icon.blue   { background: linear-gradient(135deg, var(--blue), #2563eb); }
.tile-icon.green  { background: linear-gradient(135deg, var(--green), #16a34a); }

.card h3 { font-size: 1.15rem; margin: 0 0 10px; font-weight: 700; }
.card p { color: var(--text-dim); margin: 0; font-size: 0.95rem; }

/* ─── Gallery ──────────────────────────────────────────────────────────── */

.gallery-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.shot {
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
  background: var(--bg-elevated);
  box-shadow: var(--shadow-soft);
  transition: transform 0.25s ease;
}

.shot:hover { transform: scale(1.02); }
.shot img { width: 100%; height: auto; }
.shot .caption { padding: 14px 18px; font-size: 0.85rem; color: var(--text-dim); }

/* ─── Downloads ────────────────────────────────────────────────────────── */

.download-card {
  background: linear-gradient(145deg, rgba(45, 212, 191, 0.10), rgba(167, 139, 250, 0.08));
  border: 1px solid rgba(45, 212, 191, 0.25);
  border-radius: var(--radius);
  padding: 40px;
  display: flex;
  flex-wrap: wrap;
  gap: 32px;
  align-items: center;
  justify-content: space-between;
}

.download-meta h3 { font-size: 1.4rem; margin: 0 0 8px; }
.download-meta p { color: var(--text-dim); margin: 0; }

.download-list { margin-top: 56px; display: flex; flex-direction: column; gap: 16px; }

.download-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
  padding: 22px 28px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

.download-row .name { font-weight: 700; font-size: 1.05rem; }
.download-row .desc { color: var(--text-faint); font-size: 0.85rem; margin-top: 4px; }
.download-row .actions { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }

.pill {
  font-size: 0.78rem;
  padding: 5px 12px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.06);
  color: var(--text-dim);
  border: 1px solid var(--border);
}

.pill.secure { color: var(--teal); border-color: rgba(45, 212, 191, 0.35); background: rgba(45, 212, 191, 0.08); }

.verify-box {
  margin-top: 64px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 36px;
}

.verify-box h3 { margin-top: 0; }
.verify-box pre {
  background: #050508;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 20px 24px;
  overflow-x: auto;
  font-size: 0.85rem;
  color: var(--teal);
}

.warn-box {
  margin-top: 24px;
  border: 1px solid rgba(251, 146, 60, 0.35);
  background: rgba(251, 146, 60, 0.08);
  border-radius: var(--radius-sm);
  padding: 18px 22px;
  font-size: 0.9rem;
  color: #fde3c8;
}

/* ─── Footer ───────────────────────────────────────────────────────────── */

footer {
  border-top: 1px solid var(--border);
  padding: 56px 0;
  color: var(--text-faint);
  font-size: 0.9rem;
}

.footer-grid {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 32px;
}

.footer-links { display: flex; gap: 24px; flex-wrap: wrap; }
.footer-links a:hover { color: var(--text-dim); }

/* ─── Responsive ───────────────────────────────────────────────────────── */

@media (max-width: 720px) {
  .nav-links { display: none; }
  .hero { padding: 90px 20px 70px; }
  section { padding: 64px 0; }
  .download-card { flex-direction: column; align-items: flex-start; }
}