/* Xiaoai Zhou LLC — site styles */
:root {
  --ink: #0b1f3a;
  --ink-2: #13294b;
  --text: #1c2533;
  --muted: #5a6577;
  --line: #e2e6ec;
  --bg: #ffffff;
  --bg-soft: #f6f7f9;
  --accent: #1f5fbf;
  --accent-dark: #174a96;
  --gold: #b88a3e;
  --radius: 6px;
  --max: 1160px;
  --font: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --serif: "Source Serif 4", Georgia, "Times New Roman", serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0; font-family: var(--font); color: var(--text); background: var(--bg);
  font-size: 16px; line-height: 1.7; -webkit-font-smoothing: antialiased;
}
img, svg { display: block; max-width: 100%; }
a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-dark); }
h1, h2, h3, h4 { color: var(--ink); line-height: 1.2; margin: 0 0 .6em; font-weight: 600; letter-spacing: -0.015em; }
h1, h2 { font-family: var(--serif); font-weight: 600; }
p { margin: 0 0 1em; }
.container { max-width: var(--max); margin: 0 auto; padding: 0 24px; }
.skip { position: absolute; left: -9999px; }
.skip:focus { left: 16px; top: 12px; background: #fff; padding: 8px 12px; z-index: 100; }

/* Header */
.site-header {
  position: sticky; top: 0; z-index: 50; background: rgba(255,255,255,.96);
  border-bottom: 1px solid var(--line); backdrop-filter: saturate(180%) blur(8px);
}
.site-header .container { display: flex; align-items: center; justify-content: space-between; height: 76px; }
.brand { display: flex; align-items: center; gap: 12px; color: var(--ink); }
.brand:hover { color: var(--ink); }
.brand-mark {
  width: 40px; height: 40px; border-radius: 4px; background: var(--ink); color: #fff;
  display: grid; place-items: center; font-family: var(--serif); font-weight: 700; font-size: 16px; letter-spacing: .04em;
}
.brand-name { display: flex; flex-direction: column; line-height: 1.15; }
.brand-name strong { font-size: 17px; font-weight: 700; letter-spacing: .01em; }
.brand-name span { font-size: 11.5px; color: var(--muted); letter-spacing: .14em; text-transform: uppercase; }

.nav { display: flex; align-items: center; gap: 34px; }
.nav a { color: var(--text); font-size: 15px; font-weight: 500; }
.nav a:hover, .nav a[aria-current="page"] { color: var(--accent); }
.nav .btn { color: #fff; }
.nav-toggle { display: none; background: none; border: 1px solid var(--line); border-radius: var(--radius); padding: 8px 10px; cursor: pointer; }
.nav-toggle span { display: block; width: 20px; height: 2px; background: var(--ink); margin: 4px 0; }

@media (max-width: 880px) {
  .nav-toggle { display: block; }
  .nav {
    display: none; position: absolute; top: 76px; left: 0; right: 0; background: #fff;
    flex-direction: column; align-items: stretch; gap: 0; border-bottom: 1px solid var(--line); padding: 8px 24px 20px;
  }
  .nav.open { display: flex; }
  .nav a { padding: 12px 0; border-bottom: 1px solid var(--line); }
  .nav .btn { margin-top: 14px; text-align: center; border-bottom: 0; }
}

/* Buttons */
.btn {
  display: inline-block; padding: 13px 26px; border-radius: var(--radius); font-weight: 600; font-size: 15px;
  background: var(--accent); color: #fff; border: 1px solid var(--accent); transition: background .15s, border-color .15s;
}
.btn:hover { background: var(--accent-dark); border-color: var(--accent-dark); color: #fff; }
.btn-outline { background: transparent; color: #fff; border-color: rgba(255,255,255,.45); }
.btn-outline:hover { background: rgba(255,255,255,.08); border-color: #fff; }
.btn-light { background: #fff; color: var(--ink); border-color: #fff; }
.btn-light:hover { background: #eef2f8; color: var(--ink); border-color: #eef2f8; }
.btn-sm { padding: 9px 18px; font-size: 14px; }
.link-arrow { font-weight: 600; font-size: 15px; }
.link-arrow::after { content: " →"; }

/* Hero */
.hero {
  background:
    linear-gradient(115deg, rgba(11,31,58,.97) 0%, rgba(19,41,75,.94) 55%, rgba(31,95,191,.85) 100%),
    var(--ink);
  color: #dfe6f1; position: relative; overflow: hidden;
}
.hero::after {
  content: ""; position: absolute; inset: 0; pointer-events: none;
  background-image: linear-gradient(rgba(255,255,255,.04) 1px, transparent 1px), linear-gradient(90deg, rgba(255,255,255,.04) 1px, transparent 1px);
  background-size: 56px 56px; mask-image: linear-gradient(90deg, transparent 30%, #000 100%);
}
.hero .container { position: relative; z-index: 1; padding-top: 120px; padding-bottom: 120px; }
.hero h1 { color: #fff; font-size: clamp(36px, 5.2vw, 60px); max-width: 820px; margin-bottom: 24px; }
.hero p.lead { font-size: 19px; max-width: 660px; color: #c3cee0; margin-bottom: 40px; }
.hero-actions { display: flex; gap: 14px; flex-wrap: wrap; }
.eyebrow {
  display: inline-block; font-size: 12.5px; font-weight: 600; letter-spacing: .16em; text-transform: uppercase;
  color: var(--gold); margin-bottom: 18px;
}
.hero .eyebrow { color: #e3c48d; }

.page-hero { background: var(--ink); color: #c3cee0; }
.page-hero .container { padding-top: 88px; padding-bottom: 80px; }
.page-hero h1 { color: #fff; font-size: clamp(32px, 4.4vw, 48px); max-width: 760px; }
.page-hero p { font-size: 18px; max-width: 680px; margin: 0; }
.breadcrumb { font-size: 13px; color: #8fa0bb; margin-bottom: 18px; }
.breadcrumb a { color: #b9c6db; }

/* Sections */
.section { padding: 104px 0; }
.section-soft { background: var(--bg-soft); }
.section-head { max-width: 720px; margin-bottom: 56px; }
.section-head h2 { font-size: clamp(28px, 3.4vw, 40px); }
.section-head p { color: var(--muted); font-size: 18px; margin: 0; }
.section-head.center { margin-left: auto; margin-right: auto; text-align: center; }

/* Pillars bar */
.pillars { border-bottom: 1px solid var(--line); background: #fff; }
.pillars ul {
  list-style: none; margin: 0; padding: 26px 0; display: flex; flex-wrap: wrap; justify-content: space-between; gap: 14px 28px;
  font-size: 13px; letter-spacing: .14em; text-transform: uppercase; color: var(--muted); font-weight: 600;
}

/* Grids & cards */
.grid { display: grid; gap: 28px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 980px) { .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 640px) { .grid-3, .grid-2, .grid-4 { grid-template-columns: 1fr; } }

.card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 36px 32px;
  transition: border-color .2s, box-shadow .2s;
}
.card:hover { border-color: #c9d3e1; box-shadow: 0 10px 30px -18px rgba(11,31,58,.35); }
.card h3 { font-size: 20px; margin-top: 22px; }
.card p { color: var(--muted); margin: 0; }
.card .link-arrow { display: inline-block; margin-top: 18px; }
.icon {
  width: 48px; height: 48px; border-radius: var(--radius); display: grid; place-items: center;
  background: #eaf0fa; color: var(--accent);
}
.icon svg { width: 24px; height: 24px; }

/* Split layout */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 72px; align-items: center; }
.split.top { align-items: start; }
@media (max-width: 900px) { .split { grid-template-columns: 1fr; gap: 40px; } }
.checklist { list-style: none; padding: 0; margin: 24px 0 0; }
.checklist li { position: relative; padding-left: 34px; margin-bottom: 14px; }
.checklist li::before {
  content: ""; position: absolute; left: 0; top: 5px; width: 20px; height: 20px; border-radius: 50%;
  background: #eaf0fa url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%231f5fbf' stroke-width='3' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m6 12 4 4 8-8'/%3E%3C/svg%3E") center/12px no-repeat;
}

/* Engagement models */
.model { display: flex; flex-direction: column; }
.model .tag { font-size: 12px; font-weight: 700; letter-spacing: .14em; text-transform: uppercase; color: var(--gold); }
.model h3 { margin-top: 10px; }
.model ul { margin: 18px 0 0; padding-left: 18px; color: var(--muted); font-size: 15px; }
.model ul li { margin-bottom: 6px; }
.model.featured { border-color: var(--ink); box-shadow: 0 0 0 1px var(--ink); }

/* Process */
.steps { counter-reset: step; }
.step { border-top: 2px solid var(--ink); padding-top: 24px; }
.step::before {
  counter-increment: step; content: counter(step, decimal-leading-zero);
  display: block; font-family: var(--serif); font-size: 32px; color: var(--gold); margin-bottom: 10px;
}
.step h3 { font-size: 19px; }
.step p { color: var(--muted); margin: 0; font-size: 15.5px; }

/* Panel */
.panel { background: var(--ink); color: #c3cee0; border-radius: var(--radius); padding: 44px; }
.panel h3 { color: #fff; font-size: 22px; }
.panel dl { margin: 24px 0 0; display: grid; grid-template-columns: auto 1fr; gap: 14px 24px; font-size: 15px; }
.panel dt { color: #8fa0bb; }
.panel dd { margin: 0; color: #fff; }
.panel dd a { color: #fff; border-bottom: 1px solid rgba(255,255,255,.3); }

/* Service detail */
.service-block { display: grid; grid-template-columns: 300px 1fr; gap: 56px; padding: 56px 0; border-top: 1px solid var(--line); }
.service-block:first-child { border-top: 0; padding-top: 0; }
.service-block h2 { font-size: 28px; }
.service-block .num { font-family: var(--serif); color: var(--gold); font-size: 15px; letter-spacing: .1em; margin-bottom: 10px; }
.service-block p { color: var(--muted); }
.service-block .cols { display: grid; grid-template-columns: 1fr 1fr; gap: 8px 32px; margin-top: 20px; }
@media (max-width: 900px) { .service-block { grid-template-columns: 1fr; gap: 16px; } .service-block .cols { grid-template-columns: 1fr; } }
.service-block .cols .checklist { margin: 0; }

/* Values */
.value h3 { font-size: 19px; }
.value p { color: var(--muted); margin: 0; }
.value { padding-left: 22px; border-left: 2px solid var(--gold); }

/* CTA band */
.cta-band { background: var(--ink); color: #c3cee0; }
.cta-band .container { padding-top: 88px; padding-bottom: 88px; display: flex; align-items: center; justify-content: space-between; gap: 40px; flex-wrap: wrap; }
.cta-band h2 { color: #fff; font-size: clamp(26px, 3vw, 36px); margin-bottom: 10px; }
.cta-band p { margin: 0; font-size: 17px; max-width: 620px; }

/* Contact */
.contact-card { border: 1px solid var(--line); border-radius: var(--radius); padding: 40px; }
.contact-email { font-family: var(--serif); font-size: clamp(24px, 3vw, 32px); color: var(--ink); word-break: break-all; display: inline-block; margin: 8px 0 24px; }
.contact-email:hover { color: var(--accent); }
.muted { color: var(--muted); }
.small { font-size: 14px; }

/* FAQ */
.faq details { border-bottom: 1px solid var(--line); padding: 22px 0; }
.faq details:first-child { border-top: 1px solid var(--line); }
.faq summary { cursor: pointer; font-weight: 600; color: var(--ink); font-size: 17px; list-style: none; display: flex; justify-content: space-between; gap: 20px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; font-size: 22px; line-height: 1; color: var(--accent); }
.faq details[open] summary::after { content: "−"; }
.faq details p { color: var(--muted); margin: 14px 0 0; max-width: 820px; }

/* Legal */
.legal { max-width: 800px; }
.legal h2 { font-family: var(--font); font-size: 21px; margin-top: 44px; }
.legal p, .legal li { color: #3b4657; }

/* Footer */
.site-footer { background: #08172c; color: #8fa0bb; font-size: 14.5px; }
.site-footer .container { padding-top: 72px; padding-bottom: 32px; }
.footer-grid { display: grid; grid-template-columns: 1.6fr 1fr 1fr 1fr; gap: 40px; }
@media (max-width: 880px) { .footer-grid { grid-template-columns: 1fr 1fr; } }
@media (max-width: 520px) { .footer-grid { grid-template-columns: 1fr; } }
.site-footer h4 { color: #fff; font-size: 13px; letter-spacing: .14em; text-transform: uppercase; margin-bottom: 18px; }
.site-footer ul { list-style: none; padding: 0; margin: 0; }
.site-footer li { margin-bottom: 10px; }
.site-footer a { color: #b9c6db; }
.site-footer a:hover { color: #fff; }
.site-footer .brand { color: #fff; margin-bottom: 18px; }
.site-footer .brand-mark { background: #fff; color: var(--ink); }
.site-footer .brand-name span { color: #8fa0bb; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,.08); margin-top: 56px; padding-top: 24px; display: flex; justify-content: space-between; flex-wrap: wrap; gap: 12px; font-size: 13.5px; }