/* ============================================================
   AI共创合作方案 — styles.css
   自包含纯静态样式：设计令牌 → 基础 → 组件 → 响应式
   ============================================================ */

/* ---------- Fonts ---------- */
/* 字体已在 index.html 中以非阻塞方式加载（CDN 卡顿/失败不会白屏），字体栈内置本地楷体兜底 */

:root {
  --primary-50: #E8EAF9; --primary-100: #C7CBF0; --primary-200: #A0A8E3;
  --primary-300: #7985D9; --primary-400: #5B68C8; --primary-500: #3B45A6;
  --primary-600: #2E377D; --primary-700: #222A5C; --primary-800: #171D3F; --primary-900: #0D1026;
  --neutral-0: #FFFFFF; --neutral-50: #F9F8F6; --neutral-100: #F2F0ED; --neutral-200: #E4E1DD;
  --neutral-300: #D3CFC8; --neutral-400: #A8A49E; --neutral-500: #8B8E94; --neutral-600: #5C5F66;
  --neutral-700: #3D4047; --neutral-800: #1A1D24; --neutral-900: #0F1115;
  --state-success: #16A34A; --state-warning: #D97706; --state-error: #DC2626;
  --bg: var(--neutral-50); --fg: var(--neutral-800); --card: var(--neutral-0);
  --border: var(--neutral-200); --muted: var(--neutral-100); --muted-fg: var(--neutral-600);
  --ring: var(--primary-300);
  --radius-sm: 4px; --radius-md: 8px; --radius-lg: 12px; --radius-full: 9999px;
  --font-display: 'LXGW WenKai', 'Kaiti SC', 'STKaiti', 'KaiTi', 'Inter', 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', system-ui, sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', system-ui, sans-serif;
  --container: 1200px; --nav-h: 64px;
  --shadow-sm: 0 1px 2px rgba(13,16,38,.06); --shadow-md: 0 8px 24px rgba(13,16,38,.12);
}
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; font-family: var(--font-body); font-size: 16px; line-height: 1.5; background: var(--bg); color: var(--fg); -webkit-font-smoothing: antialiased; }
body.no-scroll { overflow: hidden; }
h1,h2,h3,h4,h5,h6 { font-family: var(--font-display); font-weight: 600; letter-spacing: .02em; margin: 0; word-break: keep-all; }
p, ul { margin: 0; } ul { padding: 0; list-style: none; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
svg { display: block; }
:focus-visible { outline: 2px solid var(--ring); outline-offset: 2px; border-radius: 2px; }
section { scroll-margin-top: calc(var(--nav-h) + 16px); }
.container { max-width: var(--container); margin-inline: auto; padding-inline: 24px; }
.hidden { display: none !important; }
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; padding: 12px 24px; border-radius: var(--radius-lg); border: 1px solid transparent; font-weight: 500; font-size: 16px; line-height: 1.5; transition: background-color .2s, color .2s, border-color .2s; }
.btn .arrow { transition: transform .2s; } .btn:hover .arrow { transform: translateX(2px); }
.btn-primary { background: var(--primary-500); color: #fff; } .btn-primary:hover { background: var(--primary-600); }
.btn-primary:disabled { opacity: .7; cursor: not-allowed; }
.btn-outline { border-color: var(--border); background: #fff; color: var(--neutral-800); } .btn-outline:hover { border-color: var(--primary-300); color: var(--primary-500); }
.btn-light { background: #fff; color: var(--primary-500); padding: 16px 32px; font-weight: 600; } .btn-light:hover { background: var(--neutral-50); }
.nav { position: fixed; top: 0; left: 0; right: 0; z-index: 50; height: var(--nav-h); background: rgba(255,255,255,.9); -webkit-backdrop-filter: blur(8px); backdrop-filter: blur(8px); border-bottom: 1px solid var(--border); transition: box-shadow .25s; }
.nav.scrolled { box-shadow: var(--shadow-sm); }
.nav-inner { max-width: var(--container); margin-inline: auto; padding-inline: 24px; height: 100%; display: flex; align-items: center; justify-content: space-between; }
.nav-logo { font-family: var(--font-display); font-size: 18px; font-weight: 600; color: var(--primary-500); }
.nav-links { display: flex; align-items: center; gap: 32px; font-size: 14px; color: var(--neutral-600); }
.nav-link { transition: color .2s; } .nav-link:hover, .nav-link.active { color: var(--primary-500); } .nav-link.active { font-weight: 500; }
.nav-cta { padding: 8px 16px; background: var(--primary-500); color: #fff; border-radius: var(--radius-md); font-weight: 500; transition: background-color .2s; }
.nav-cta:hover { background: var(--primary-600); }
.nav-toggle { display: none; padding: 8px; color: var(--neutral-700); border-radius: var(--radius-sm); }
.nav-toggle .icon-x { display: none; }
.nav-toggle.open .icon-menu { display: none; } .nav-toggle.open .icon-x { display: block; }
.hero { position: relative; min-height: 90vh; display: flex; align-items: center; padding-top: var(--nav-h); background: url("assets/hero.jpg") center / cover no-repeat; }
.hero-overlay { position: absolute; inset: 0; background: linear-gradient(to bottom right, rgba(255,255,255,.85), rgba(255,255,255,.7) 50%, rgba(232,234,249,.6)); }
.hero .container { position: relative; }
.hero-content { max-width: 768px; padding: 96px 0; }
.eyebrow { font-size: 14px; font-weight: 500; letter-spacing: .1em; color: var(--primary-500); margin-bottom: 16px; }
.hero-title { font-size: 36px; line-height: 1.25; margin-bottom: 24px; }
.text-gradient { background: linear-gradient(135deg, var(--primary-500), var(--primary-300)); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; color: transparent; }
.hero-sub { font-size: 18px; color: var(--neutral-700); line-height: 1.625; margin-bottom: 32px; max-width: 672px; }
.hero-desc { font-size: 16px; color: var(--neutral-600); margin-bottom: 40px; max-width: 672px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 16px; }
.section { padding: 80px 0; } .section-tinted { background: var(--neutral-100); }
.section-head { margin-bottom: 56px; } .section-head--faq { margin-bottom: 40px; }
.section-eyebrow { font-size: 14px; font-weight: 500; letter-spacing: .1em; color: var(--primary-500); margin-bottom: 12px; }
.section-title { font-size: 30px; margin-bottom: 24px; }
.section-lead { font-size: 18px; color: var(--neutral-700); line-height: 1.625; max-width: 768px; }
.table-wrap { overflow-x: auto; background: #fff; border: 1px solid var(--border); border-radius: var(--radius-md); -webkit-overflow-scrolling: touch; }
.table-wrap--xl { border-radius: var(--radius-lg); }
.table-min-320 { min-width: 320px; } .table-min-480 { min-width: 480px; } .table-min-680 { min-width: 680px; }
.data-table { width: 100%; border-collapse: collapse; font-variant-numeric: tabular-nums; }
.data-table th, .data-table td { padding: 14px 16px; text-align: left; border-bottom: 1px solid var(--border); word-break: break-word; }
.data-table tbody tr:last-child td { border-bottom: 0; }
.data-table th { font-weight: 600; color: var(--neutral-700); background: var(--neutral-100); white-space: nowrap; }
.data-table tbody tr:hover { background: var(--neutral-50); }
.td-strong { font-weight: 600; } .td-success { color: var(--state-success); font-weight: 600; } .td-primary { color: var(--primary-500); font-weight: 600; }
.table-note { font-size: 14px; color: var(--neutral-600); margin: 16px 0 48px; }
.card { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius-lg); }
.icon-box { width: 40px; height: 40px; border-radius: var(--radius-md); background: var(--primary-50); color: var(--primary-500); display: flex; align-items: center; justify-content: center; margin-bottom: 16px; flex-shrink: 0; }
.value-grid { display: grid; gap: 24px; grid-template-columns: 1fr; }
.value-card { padding: 24px; transition: transform .2s, box-shadow .2s; }
.value-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-sm); }
.card-title-lg { font-size: 20px; margin-bottom: 8px; }
.card-text { color: var(--neutral-600); }
.steps { display: flex; flex-direction: column; gap: 40px; }
.step-card { padding: 24px; }
.step-head { display: flex; align-items: flex-start; gap: 16px; }
.step-num { flex-shrink: 0; width: 40px; height: 40px; border-radius: var(--radius-full); background: var(--primary-500); color: #fff; display: flex; align-items: center; justify-content: center; font-weight: 600; font-variant-numeric: tabular-nums; }
.step-title { font-size: 24px; } .step-price { color: var(--primary-500); font-weight: 500; margin-top: 4px; }
.step-cols { display: grid; gap: 32px; margin-top: 24px; }
.step-sub { font-family: var(--font-body); font-weight: 600; font-size: 16px; margin-bottom: 12px; color: var(--neutral-800); }
.check-list { display: grid; gap: 8px; color: var(--neutral-700); }
.check-list li { display: flex; gap: 8px; }
.check-list svg { flex-shrink: 0; margin-top: 5px; color: var(--primary-500); }
.rule-note { font-size: 14px; color: var(--neutral-600); margin-bottom: 12px; }
.step-note { margin-top: 24px; padding: 16px; background: var(--neutral-50); border-radius: var(--radius-md); font-size: 14px; color: var(--neutral-700); }
.options { display: grid; gap: 24px; margin-top: 24px; }
.option { padding: 20px; border: 1px solid var(--border); border-radius: var(--radius-md); }
.option--featured { border: 2px solid var(--primary-300); background: rgba(232,234,249,.3); }
.option-title { display: flex; align-items: center; flex-wrap: wrap; gap: 8px; font-family: var(--font-display); font-size: 18px; font-weight: 600; margin-bottom: 8px; }
.badge { padding: 2px 8px; background: var(--primary-500); color: #fff; font-size: 12px; font-weight: 500; border-radius: var(--radius-full); font-family: var(--font-body); letter-spacing: 0; }
.option-desc { font-size: 14px; color: var(--neutral-600); margin-bottom: 12px; }
.option--featured .option-desc { color: var(--neutral-700); }
.option ul { display: grid; gap: 4px; font-size: 14px; color: var(--neutral-700); }
.option-conclusion { margin-top: 12px; font-size: 14px; font-weight: 500; color: var(--neutral-800); }
.formula { margin: 12px 0; padding: 12px; background: #fff; border: 1px solid var(--border); border-radius: var(--radius-md); }
.formula-label { font-size: 14px; color: var(--neutral-600); }
.formula-value { font-family: var(--font-display); font-size: 20px; font-weight: 600; color: var(--primary-500); }
.step-table { margin-top: 24px; }
.step-extra { margin-top: 24px; display: grid; gap: 16px; font-size: 14px; color: var(--neutral-700); }
.service-box { padding: 16px; background: var(--neutral-50); border-radius: var(--radius-md); }
.service-box ul { margin-top: 8px; display: grid; gap: 4px; }
.feature-grid { display: grid; gap: 24px; grid-template-columns: 1fr; }
.feature-card { padding: 24px; }
.feature-card .card-title-lg { margin-bottom: 12px; }
.feature-body { color: var(--neutral-700); margin-bottom: 16px; } .feature-body:last-child { margin-bottom: 0; }
.feature-note { font-size: 14px; color: var(--neutral-600); }
.feature-table { margin-top: 16px; }
.info-box { padding: 16px; background: var(--neutral-50); border-radius: var(--radius-md); font-size: 14px; }
.info-box-title { font-weight: 600; margin-bottom: 8px; }
.risk-grid { display: grid; gap: 24px; grid-template-columns: 1fr; }
.risk-card { padding: 24px; } .risk-card h3 { font-size: 18px; margin-bottom: 8px; } .risk-card p { color: var(--neutral-700); }
.risk-footnote { margin-top: 32px; text-align: center; color: var(--neutral-700); }
.faq-list { display: grid; gap: 16px; max-width: 896px; }
.faq-item { background: #fff; border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 0 24px; transition: border-color .2s; }
.faq-item:hover { border-color: var(--primary-300); }
.faq-q { width: 100%; display: flex; align-items: center; justify-content: space-between; gap: 16px; padding: 24px 0; text-align: left; font-weight: 600; font-size: 18px; color: var(--primary-500); }
.faq-chevron { flex-shrink: 0; color: var(--neutral-400); transition: transform .3s; }
.faq-item.collapsed .faq-chevron { transform: rotate(-90deg); }
.faq-a { display: grid; grid-template-rows: 1fr; transition: grid-template-rows .3s; }
.faq-item.collapsed .faq-a { grid-template-rows: 0fr; }
.faq-a-inner { overflow: hidden; } .faq-a-inner p { padding-bottom: 24px; color: var(--neutral-700); }
.next { background: var(--primary-500); color: #fff; padding: 80px 0; text-align: center; }
.next-title { font-size: 30px; margin-bottom: 24px; color: #fff; }
.next-lead { font-size: 18px; color: rgba(255,255,255,.9); max-width: 672px; margin: 0 auto 32px; line-height: 1.625; }
.next-mail { display: block; margin-top: 16px; font-size: 14px; color: rgba(255,255,255,.8); }
.next-mail:hover { color: #fff; text-decoration: underline; }
.next-note { margin-top: 24px; font-size: 14px; color: rgba(255,255,255,.7); }
.next-tagline { margin-top: 8px; font-size: 16px; font-weight: 500; color: rgba(255,255,255,.9); }
.footer { padding: 40px 0; border-top: 1px solid var(--border); background: var(--neutral-0); }
.footer-inner { display: flex; flex-direction: column; align-items: center; justify-content: space-between; gap: 16px; }
.footer-logo { font-family: var(--font-display); color: var(--primary-500); font-weight: 600; }
.footer-copy { font-size: 14px; color: var(--neutral-500); }
.modal { position: fixed; inset: 0; z-index: 100; display: flex; align-items: center; justify-content: center; padding: 24px; background: rgba(13,16,38,.5); -webkit-backdrop-filter: blur(4px); backdrop-filter: blur(4px); opacity: 0; visibility: hidden; transition: opacity .25s, visibility .25s; }
.modal.show { opacity: 1; visibility: visible; }
.modal-dialog { position: relative; width: 100%; max-width: 480px; max-height: calc(100vh - 48px); overflow-y: auto; background: #fff; border-radius: var(--radius-lg); padding: 32px; box-shadow: var(--shadow-md); transform: translateY(12px) scale(.98); transition: transform .25s; }
.modal.show .modal-dialog { transform: none; }
.modal-close { position: absolute; top: 16px; right: 16px; padding: 8px; color: var(--neutral-500); border-radius: var(--radius-sm); transition: color .2s, background-color .2s; }
.modal-close:hover { color: var(--neutral-800); background: var(--muted); }
.modal-title { font-size: 24px; margin-bottom: 8px; }
.modal-desc { font-size: 14px; color: var(--neutral-600); margin-bottom: 24px; }
.field { display: block; margin-bottom: 16px; font-size: 14px; font-weight: 500; color: var(--neutral-700); }
.field input, .field textarea { display: block; width: 100%; margin-top: 6px; padding: 10px 12px; font: inherit; font-weight: 400; color: var(--fg); background: #fff; border: 1px solid var(--border); border-radius: var(--radius-md); transition: border-color .2s, box-shadow .2s; resize: vertical; }
.field input:focus, .field textarea:focus { outline: none; border-color: var(--primary-300); box-shadow: 0 0 0 3px rgba(121,133,217,.25); }
.field .field-error { display: none; margin-top: 6px; font-size: 12px; font-weight: 400; color: var(--state-error); }
.field.invalid .field-error { display: block; }
.field.invalid input, .field.invalid textarea { border-color: var(--state-error); }
.modal-submit { width: 100%; }
.modal-success { display: none; text-align: center; padding: 16px 0 8px; } .modal-success.show { display: block; }
.success-icon { width: 56px; height: 56px; margin: 0 auto 16px; border-radius: var(--radius-full); background: rgba(22,163,74,.1); color: var(--state-success); display: flex; align-items: center; justify-content: center; }
.modal-done { margin-top: 8px; }
.toast { position: fixed; left: 50%; bottom: 32px; z-index: 120; transform: translate(-50%, 8px); max-width: calc(100vw - 48px); background: var(--neutral-800); color: #fff; font-size: 14px; padding: 10px 20px; border-radius: var(--radius-full); box-shadow: var(--shadow-md); opacity: 0; visibility: hidden; transition: opacity .3s, transform .3s, visibility .3s; }
.toast.show { opacity: 1; visibility: visible; transform: translate(-50%, 0); }
.to-top { position: fixed; right: 24px; bottom: 24px; z-index: 60; width: 44px; height: 44px; border-radius: var(--radius-full); background: #fff; border: 1px solid var(--border); color: var(--primary-500); display: flex; align-items: center; justify-content: center; box-shadow: var(--shadow-sm); opacity: 0; visibility: hidden; transform: translateY(8px); transition: opacity .25s, transform .25s, visibility .25s, border-color .2s; }
.to-top.show { opacity: 1; visibility: visible; transform: none; } .to-top:hover { border-color: var(--primary-300); }
.reveal { opacity: 0; transform: translateY(24px); transition: opacity .6s ease-out, transform .6s ease-out; }
.reveal.visible { opacity: 1; transform: none; }
@media (min-width: 768px) {
  .hero-content { padding: 128px 0; } .hero-title { font-size: 48px; } .hero-sub { font-size: 20px; }
  .section { padding: 112px 0; } .section-title { font-size: 36px; }
  .value-grid { grid-template-columns: repeat(3, 1fr); }
  .step-card { padding: 32px; } .step-cols { grid-template-columns: 1fr 1fr; }
  .options { grid-template-columns: 1fr 1fr; }
  .feature-grid { grid-template-columns: repeat(2, 1fr); } .feature-card { padding: 32px; }
  .risk-grid { grid-template-columns: repeat(3, 1fr); }
  .next { padding: 112px 0; } .next-title { font-size: 36px; } .next-lead { font-size: 20px; }
  .footer-inner { flex-direction: row; }
}
@media (min-width: 1024px) { .hero-title { font-size: 60px; } }
@media (max-width: 767px) {
  .nav-toggle { display: inline-flex; }
  .nav-links { display: none; position: absolute; top: var(--nav-h); left: 0; right: 0; flex-direction: column; align-items: stretch; gap: 0; background: #fff; padding: 8px 24px 20px; border-bottom: 1px solid var(--border); box-shadow: var(--shadow-md); }
  .nav-links.open { display: flex; }
  .nav-links .nav-link { padding: 14px 0; font-size: 15px; border-bottom: 1px solid var(--muted); }
  .nav-links .nav-cta { margin-top: 20px; text-align: center; border-bottom: 0; }
  .hero { min-height: 88vh; } .hero-actions .btn { flex: 1 1 auto; }
  .faq-q { font-size: 16px; padding: 20px 0; } .faq-item { padding: 0 20px; } .faq-a-inner p { padding-bottom: 20px; }
  .modal-dialog { padding: 24px; } .to-top { right: 16px; bottom: 16px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
  .reveal { opacity: 1; transform: none; }
}