:root {
  --bg: #f7f8f6;
  --surface: #ffffff;
  --ink: #0e1b24;
  --ink-soft: #4a5a66;
  --line: #dfe4e2;
  --brand: #0f766e;
  --brand-ink: #ffffff;
  --accent: #f2a541;
  --deep: #0b2230;
  --deep-ink: #e8f0ef;
  --radius: 14px;
  --max: 1120px;
  --font: "Inter", system-ui, -apple-system, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0a141b;
    --surface: #111e27;
    --ink: #e8eef0;
    --ink-soft: #9fb0ba;
    --line: #1f313c;
    --brand: #2dd4bf;
    --brand-ink: #062a27;
    --deep: #06121a;
    --deep-ink: #e8f0ef;
  }
}

* { 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: 1.6;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; }
img, svg { display: block; max-width: 100%; }

.wrap { width: 100%; max-width: var(--max); margin: 0 auto; padding: 0 20px; }

/* Header */
.site-header {
  position: sticky; top: 0; z-index: 10;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(160%) blur(10px);
  border-bottom: 1px solid var(--line);
}
.site-header .wrap { display: flex; align-items: center; gap: 24px; height: 64px; }
.logo { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 19px; text-decoration: none; letter-spacing: -0.01em; }
.logo svg { width: 28px; height: 28px; }
.nav { display: flex; gap: 22px; margin-left: auto; }
.nav a { text-decoration: none; color: var(--ink-soft); font-size: 15px; }
.nav a:hover { color: var(--ink); }
.lang { font-size: 14px; text-decoration: none; border: 1px solid var(--line); border-radius: 999px; padding: 4px 12px; color: var(--ink-soft); }
.lang:hover { color: var(--ink); border-color: var(--ink-soft); }

.btn {
  display: inline-block; text-decoration: none; font-weight: 600;
  background: var(--brand); color: var(--brand-ink);
  padding: 12px 22px; border-radius: 999px; font-size: 16px;
  transition: transform .15s ease, opacity .15s ease;
}
.btn:hover { transform: translateY(-1px); opacity: .92; }
.btn.ghost { background: transparent; color: var(--ink); border: 1px solid var(--line); }
.btn.small { padding: 8px 16px; font-size: 14px; }

/* Hero */
.hero { padding: 96px 0 80px; position: relative; overflow: hidden; }
.hero::before {
  content: ""; position: absolute; inset: -40% -10% auto auto; width: 620px; height: 620px;
  background: radial-gradient(closest-side, color-mix(in srgb, var(--brand) 22%, transparent), transparent);
  pointer-events: none;
}
.eyebrow { display: inline-block; font-size: 13px; font-weight: 600; letter-spacing: .08em; text-transform: uppercase; color: var(--brand); margin-bottom: 18px; }
.hero h1 { font-size: clamp(36px, 6vw, 64px); line-height: 1.05; letter-spacing: -0.03em; margin: 0 0 22px; max-width: 16ch; }
.hero p.lead { font-size: clamp(18px, 2.2vw, 21px); color: var(--ink-soft); max-width: 58ch; margin: 0 0 34px; }
.hero .actions { display: flex; gap: 12px; flex-wrap: wrap; }
.tags { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 44px; padding: 0; list-style: none; }
.tags li { font-size: 14px; border: 1px solid var(--line); border-radius: 999px; padding: 5px 13px; color: var(--ink-soft); background: var(--surface); }

/* Sections */
section { padding: 88px 0; }
.section-head { max-width: 680px; margin-bottom: 44px; }
.section-head h2 { font-size: clamp(28px, 4vw, 40px); letter-spacing: -0.02em; line-height: 1.15; margin: 0 0 14px; }
.section-head p { color: var(--ink-soft); margin: 0; font-size: 18px; }

.grid { display: grid; gap: 18px; grid-template-columns: repeat(3, 1fr); }
.card {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 28px;
}
.card .icon {
  width: 44px; height: 44px; border-radius: 12px; display: grid; place-items: center;
  background: color-mix(in srgb, var(--brand) 14%, transparent); color: var(--brand); margin-bottom: 18px;
}
.card .icon svg { width: 22px; height: 22px; }
.card h3 { margin: 0 0 8px; font-size: 20px; letter-spacing: -0.01em; }
.card p { margin: 0; color: var(--ink-soft); font-size: 16px; }
.card ul { margin: 14px 0 0; padding-left: 18px; color: var(--ink-soft); font-size: 15px; }

/* AI band */
.band { background: var(--deep); color: var(--deep-ink); }
.band .section-head p, .band .card p, .band .card ul { color: color-mix(in srgb, var(--deep-ink) 72%, transparent); }
.band .card { background: color-mix(in srgb, var(--deep-ink) 5%, transparent); border-color: color-mix(in srgb, var(--deep-ink) 12%, transparent); }
.band .eyebrow { color: var(--accent); }
.band .card .icon { background: color-mix(in srgb, var(--accent) 18%, transparent); color: var(--accent); }

/* Steps */
.steps { counter-reset: step; display: grid; gap: 18px; grid-template-columns: repeat(4, 1fr); }
.step { border-top: 2px solid var(--brand); padding-top: 18px; }
.step::before { counter-increment: step; content: "0" counter(step); font-size: 14px; font-weight: 700; color: var(--brand); }
.step h3 { margin: 8px 0 6px; font-size: 19px; }
.step p { margin: 0; color: var(--ink-soft); font-size: 15px; }

/* Why */
.why { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px 40px; }
.why div { display: flex; gap: 14px; }
.why svg { flex: none; width: 22px; height: 22px; color: var(--brand); margin-top: 3px; }
.why h3 { margin: 0 0 4px; font-size: 18px; }
.why p { margin: 0; color: var(--ink-soft); font-size: 16px; }

/* CTA */
.cta {
  background: var(--surface); border: 1px solid var(--line); border-radius: 24px;
  padding: 56px; display: flex; align-items: center; justify-content: space-between; gap: 32px;
}
.cta h2 { margin: 0 0 10px; font-size: clamp(26px, 3.4vw, 36px); letter-spacing: -0.02em; }
.cta p { margin: 0; color: var(--ink-soft); max-width: 52ch; }
.cta .email { font-size: 15px; color: var(--ink-soft); margin-top: 12px; text-align: center; }

/* Footer */
footer { border-top: 1px solid var(--line); padding: 32px 0; font-size: 14px; color: var(--ink-soft); }
footer .wrap { display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; }

/* Hero highlights */
.hero-points { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; margin-top: 48px; max-width: 880px; }
.hero-points div { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px 18px; }
.hero-points strong { display: block; font-size: 16px; }
.hero-points span { color: var(--ink-soft); font-size: 14px; }

/* AI use cases */
.usecases { display: grid; gap: 14px; grid-template-columns: repeat(4, 1fr); margin-top: 18px; }
.usecase { border-radius: 12px; padding: 18px; background: color-mix(in srgb, var(--deep-ink) 4%, transparent); border: 1px solid color-mix(in srgb, var(--deep-ink) 10%, transparent); }
.usecase h4 { margin: 0 0 6px; font-size: 16px; color: var(--deep-ink); }
.usecase p { margin: 0; font-size: 14px; color: color-mix(in srgb, var(--deep-ink) 70%, transparent); }
.subhead { margin: 56px 0 6px; font-size: 22px; letter-spacing: -0.01em; }
.subnote { margin: 0; color: color-mix(in srgb, var(--deep-ink) 70%, transparent); }

/* Industries */
.chips { display: flex; flex-wrap: wrap; gap: 10px; padding: 0; margin: 0; list-style: none; }
.chips li { background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 12px 16px; font-size: 15px; }
.chips li b { display: block; font-size: 16px; }
.chips li span { color: var(--ink-soft); font-size: 14px; }

/* FAQ */
.faq { max-width: 820px; }
.faq details { border-bottom: 1px solid var(--line); padding: 18px 0; }
.faq summary { cursor: pointer; font-weight: 600; font-size: 18px; list-style: none; display: flex; justify-content: space-between; gap: 16px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; color: var(--brand); font-size: 22px; line-height: 1; }
.faq details[open] summary::after { content: "–"; }
.faq details p { margin: 12px 0 0; color: var(--ink-soft); }

/* 404 */
.notfound { min-height: 70vh; display: grid; place-items: center; text-align: center; }
.notfound h1 { font-size: 56px; margin: 0 0 8px; }

@media (max-width: 900px) {
  .grid { grid-template-columns: repeat(2, 1fr); }
  .steps, .usecases { grid-template-columns: repeat(2, 1fr); }
  .nav { display: none; }
  .site-header .wrap { justify-content: space-between; }
  .site-header .lang { margin-left: auto; }
}
@media (max-width: 620px) {
  body { font-size: 16px; }
  .wrap { padding: 0 16px; }
  .grid, .steps, .why, .usecases, .hero-points { grid-template-columns: 1fr; }
  section { padding: 64px 0; }
  .hero { padding: 64px 0 56px; }
  .cta { flex-direction: column; align-items: flex-start; padding: 32px 24px; }
  .site-header .btn.small { display: none; }
}