/* ===== AI有数 · 设计系统 ===== */
:root {
  --c-primary: #4f46e5;
  --c-primary-dark: #3730a3;
  --c-cyan: #22d3ee;
  --c-ink: #1e1b3a;
  --c-body: #55527a;
  --c-bg: #f6f6fd;
  --c-surface: #ffffff;
  --c-line: #e7e6f4;
  --c-hero-bg: linear-gradient(150deg, #1e1b3a 0%, #312e81 50%, #4f46e5 100%);
  --radius: 16px;
  --radius-sm: 10px;
  --shadow: 0 20px 50px -20px rgba(79, 70, 229, 0.4);
  --shadow-sm: 0 8px 24px -12px rgba(30, 27, 58, 0.18);
  --maxw: 1140px;
  --font: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font);
  color: var(--c-ink);
  background: var(--c-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }

.container { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }
.container.narrow { max-width: 820px; }

/* Header */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--c-line);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 68px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 18px; color: var(--c-ink); }
.brand-logo { width: 34px; height: 34px; }
.brand-name { letter-spacing: 0.5px; }
.main-nav { display: flex; align-items: center; gap: 28px; }
.main-nav a { font-size: 15px; color: var(--c-body); transition: color .2s; }
.main-nav a:hover { color: var(--c-primary); }
.nav-cta { background: var(--c-primary); color: #fff !important; padding: 8px 20px; border-radius: 999px; font-weight: 600; transition: background .2s, transform .2s; }
.nav-cta:hover { background: var(--c-primary-dark); transform: translateY(-1px); }
.nav-toggle { display: none; background: none; border: none; cursor: pointer; flex-direction: column; gap: 5px; }
.nav-toggle span { width: 24px; height: 2px; background: var(--c-ink); border-radius: 2px; transition: .3s; }

/* Hero */
.hero { background: var(--c-hero-bg); color: #fff; overflow: hidden; position: relative; }
.hero-grid-bg {
  position: absolute; inset: 0; opacity: .12;
  background-image: linear-gradient(rgba(255,255,255,.4) 1px, transparent 1px), linear-gradient(90deg, rgba(255,255,255,.4) 1px, transparent 1px);
  background-size: 48px 48px;
  -webkit-mask-image: radial-gradient(circle at 60% 40%, #000, transparent 70%);
  mask-image: radial-gradient(circle at 60% 40%, #000, transparent 70%);
}
.hero-inner { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 48px; align-items: center; padding: 96px 24px; position: relative; }
.hero-text .eyebrow { color: var(--c-cyan); }
.hero-text h1 { font-size: 50px; line-height: 1.15; margin: 16px 0 20px; letter-spacing: -1px; }
.hero-text h1 .accent { background: linear-gradient(90deg, #22d3ee, #a5b4fc); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }
.hero-desc { font-size: 17px; color: rgba(255, 255, 255, 0.9); max-width: 520px; }
.hero-actions { display: flex; gap: 14px; margin-top: 32px; flex-wrap: wrap; }

.btn { display: inline-block; padding: 13px 30px; border-radius: 999px; font-weight: 600; font-size: 15px; transition: transform .2s, box-shadow .2s, background .2s; }
.btn:hover { transform: translateY(-2px); }
.btn-primary { background: #22d3ee; color: #1e1b3a; box-shadow: 0 12px 30px -10px rgba(34, 211, 238, 0.6); }
.btn-primary:hover { background: #67e8f9; }
.btn-ghost { background: rgba(255, 255, 255, 0.14); color: #fff; border: 1px solid rgba(255, 255, 255, 0.35); }
.btn-ghost:hover { background: rgba(255, 255, 255, 0.24); }
.btn-light { background: #fff; color: var(--c-primary-dark); }
.btn-light:hover { box-shadow: var(--shadow-sm); }

/* AI Orb */
.hero-visual { position: relative; display: flex; align-items: center; justify-content: center; min-height: 340px; }
.ai-orb { position: relative; width: 220px; height: 220px; }
.orb-core {
  position: absolute; inset: 40px; border-radius: 50%;
  background: radial-gradient(circle at 35% 30%, #a5b4fc, #4f46e5 60%, #22d3ee);
  box-shadow: 0 0 60px rgba(165, 180, 252, 0.6);
}
.orb-ring { position: absolute; border-radius: 50%; border: 1px solid rgba(255,255,255,0.4); }
.orb-ring.r1 { inset: 20px; animation: spin 10s linear infinite; border-top-color: #22d3ee; border-bottom-color: #a5b4fc; }
.orb-ring.r2 { inset: 0; animation: spin 16s linear infinite reverse; border-left-color: #22d3ee; }
.orb-ring.r3 { inset: 8px; border-style: dashed; animation: spin 22s linear infinite; border-color: rgba(255,255,255,0.35); }
@keyframes spin { to { transform: rotate(360deg); } }
.float-chip {
  position: absolute; background: rgba(255, 255, 255, 0.14); border: 1px solid rgba(255, 255, 255, 0.3);
  padding: 8px 16px; border-radius: 999px; font-size: 13px; font-weight: 600; backdrop-filter: blur(6px);
}
.chip-1 { top: 8%; left: 2%; }
.chip-2 { top: 46%; right: 0; }
.chip-3 { bottom: 6%; left: 10%; }

/* Sections */
.section { padding: 96px 0; }
.section-head { text-align: center; max-width: 640px; margin: 0 auto 56px; }
.section-head h2 { font-size: 38px; letter-spacing: -0.5px; margin: 12px 0; }
.section-sub { color: var(--c-body); font-size: 16px; }
.eyebrow { color: var(--c-primary); font-weight: 700; font-size: 13px; letter-spacing: 2px; text-transform: uppercase; }

.cards-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.card { background: var(--c-surface); border: 1px solid var(--c-line); border-radius: var(--radius); padding: 30px 26px; box-shadow: var(--shadow-sm); transition: transform .25s, box-shadow .25s; }
.card:hover { transform: translateY(-6px); box-shadow: var(--shadow); }
.card-icon { font-size: 34px; margin-bottom: 14px; }
.card h3 { font-size: 19px; margin-bottom: 10px; }
.card p { color: var(--c-body); font-size: 14.5px; }

/* Features */
.features { background: #fff; }
.feature-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.feature-card { background: linear-gradient(160deg, #f6f6fd, #eef0ff); border: 1px solid var(--c-line); border-radius: var(--radius); padding: 30px 26px; transition: transform .25s, box-shadow .25s; }
.feature-card:hover { transform: translateY(-6px); box-shadow: var(--shadow); }
.f-icon { font-size: 36px; margin-bottom: 14px; }
.feature-card h3 { font-size: 19px; margin-bottom: 10px; }
.feature-card p { color: var(--c-body); font-size: 14.5px; }

/* How */
.how { background: var(--c-hero-bg); color: #fff; }
.how .eyebrow { color: var(--c-cyan); }
.how .section-sub { color: rgba(255, 255, 255, 0.8); }
.steps { list-style: none; display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.step { background: rgba(255, 255, 255, 0.08); border: 1px solid rgba(255, 255, 255, 0.18); border-radius: var(--radius); padding: 32px 28px; }
.step-num { font-size: 40px; font-weight: 800; color: #22d3ee; }
.step h3 { margin: 12px 0 8px; font-size: 21px; }
.step p { color: rgba(255, 255, 255, 0.82); font-size: 15px; }

/* FAQ */
.faq-list { display: flex; flex-direction: column; gap: 14px; }
.faq-item { background: var(--c-surface); border: 1px solid var(--c-line); border-radius: var(--radius-sm); padding: 6px 24px; box-shadow: var(--shadow-sm); }
.faq-item summary { cursor: pointer; font-weight: 600; padding: 16px 0; list-style: none; display: flex; justify-content: space-between; align-items: center; }
.faq-item summary::after { content: "+"; font-size: 24px; color: var(--c-primary); font-weight: 400; transition: transform .2s; }
.faq-item[open] summary::after { transform: rotate(45deg); }
.faq-item p { padding: 0 0 18px; color: var(--c-body); font-size: 15px; }

/* CTA */
.cta { background: var(--c-hero-bg); color: #fff; text-align: center; }
.cta h2 { font-size: 38px; margin-bottom: 12px; }
.cta p { color: rgba(255, 255, 255, 0.9); margin-bottom: 28px; }

/* Footer */
.site-footer { background: #141227; color: rgba(255, 255, 255, 0.75); padding: 56px 0 32px; }
.footer-inner { text-align: center; }
.footer-brand { display: flex; align-items: center; justify-content: center; gap: 10px; font-size: 18px; font-weight: 700; color: #fff; margin-bottom: 14px; }
.footer-brand .brand-logo { width: 28px; height: 28px; }
.footer-desc { max-width: 460px; margin: 0 auto 24px; font-size: 14px; }
.footer-links { display: flex; justify-content: center; gap: 24px; flex-wrap: wrap; margin-bottom: 24px; font-size: 14px; }
.footer-links a:hover { color: #fff; }
.copyright { font-size: 13px; opacity: .7; }
.beian { margin-top: 8px; font-size: 13px; }
.beian a { color: rgba(255, 255, 255, 0.6); }
.beian a:hover { color: #fff; }

/* 滚动出现动画 */
.reveal { opacity: 0; transform: translateY(24px); transition: opacity .6s ease, transform .6s ease; }
.reveal.in-view { opacity: 1; transform: translateY(0); }

/* Responsive */
@media (max-width: 960px) {
  .hero-inner { grid-template-columns: 1fr; text-align: center; padding: 64px 24px; }
  .hero-desc { margin: 0 auto; }
  .hero-actions { justify-content: center; }
  .hero-visual { min-height: 240px; }
  .cards-grid, .feature-grid { grid-template-columns: 1fr 1fr; }
  .steps { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  .main-nav { position: fixed; top: 68px; right: 0; left: 0; background: #fff; flex-direction: column; padding: 20px 24px; gap: 18px; border-bottom: 1px solid var(--c-line); transform: translateY(-130%); transition: transform .3s; }
  .main-nav.open { transform: translateY(0); }
  .nav-toggle { display: flex; }
  .hero-text h1 { font-size: 36px; }
  .cards-grid, .feature-grid { grid-template-columns: 1fr; }
  .section-head h2, .cta h2 { font-size: 30px; }
}