/* ==========================================================================
   fre:ac 中文站 www.freac.cn — 全站样式
   品牌色取自 fre:ac 官方 logo（#4B6AA6 钢蓝）
   扁平 · 现代 · 专业 · 浅色主题 · 无 emoji
   ========================================================================== */

:root {
  --brand: #4B6AA6;
  --brand-dark: #3A5387;
  --brand-deep: #2A3C64;
  --brand-light: #EDF1F8;
  --brand-lighter: #F6F8FC;
  --brand-border: #D7DFEC;
  --accent: #6E8CC7;
  --text: #24303F;
  --text-secondary: #55637A;
  --text-muted: #7C889E;
  --white: #ffffff;
  --bg: #ffffff;
  --bg-soft: #F6F8FC;
  --border: #E4E9F1;
  --green: #2E8B57;
  --radius: 10px;
  --radius-lg: 16px;
  --shadow: 0 2px 12px rgba(42, 60, 100, 0.08);
  --shadow-lg: 0 10px 36px rgba(42, 60, 100, 0.14);
  --container: 1140px;
  --font-sans: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Noto Sans SC",
    -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: "SF Mono", "JetBrains Mono", Consolas, "Courier New", monospace;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.75;
  color: var(--text);
  background: var(--bg);
}

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

a { color: var(--brand); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--brand-dark); }

ul, ol { padding-left: 1.3em; }

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

/* ---------------- 头部导航 ---------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: saturate(1.6) blur(10px);
  -webkit-backdrop-filter: saturate(1.6) blur(10px);
  border-bottom: 1px solid var(--border);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
  gap: 24px;
}

.brand { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.brand img { height: 34px; width: auto; }
.brand .brand-name { font-size: 20px; font-weight: 700; color: var(--text); letter-spacing: 0.2px; }
.brand .brand-name .colon { color: var(--brand); }

.nav-links { display: flex; align-items: center; gap: 6px; list-style: none; padding: 0; }
.nav-links a {
  display: block;
  padding: 8px 16px;
  border-radius: 8px;
  font-size: 15px;
  color: var(--text-secondary);
  font-weight: 500;
}
.nav-links a:hover { color: var(--brand); background: var(--brand-light); }
.nav-links a.active { color: var(--brand); background: var(--brand-light); font-weight: 600; }

.nav-cta {
  display: inline-block;
  padding: 9px 22px;
  border-radius: 8px;
  background: var(--brand);
  color: var(--white) !important;
  font-size: 14px;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: background 0.2s;
}
.nav-cta:hover { background: var(--brand-dark); color: var(--white) !important; }

.nav-toggle {
  display: none;
  background: none;
  border: none;
  padding: 8px;
  cursor: pointer;
}
.nav-toggle span,
.nav-toggle span::before,
.nav-toggle span::after {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  position: relative;
  transition: transform 0.25s, opacity 0.25s;
}
.nav-toggle span::before { content: ""; position: absolute; top: -7px; }
.nav-toggle span::after { content: ""; position: absolute; top: 7px; }

/* ---------------- 按钮体系 ---------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 34px;
  border-radius: 8px;
  font-size: 16px;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background 0.2s, border-color 0.2s, color 0.2s, box-shadow 0.2s;
  font-family: inherit;
  line-height: 1.4;
}
.btn-primary {
  background: var(--brand);
  color: var(--white);
  box-shadow: 0 4px 14px rgba(75, 106, 166, 0.35);
}
.btn-primary:hover { background: var(--brand-dark); color: var(--white); }
.btn-secondary {
  background: var(--white);
  color: var(--brand);
  border-color: var(--brand-border);
}
.btn-secondary:hover { border-color: var(--brand); color: var(--brand-dark); }
.btn-ghost { background: transparent; color: var(--white); border-color: rgba(255,255,255,.5); }
.btn-ghost:hover { border-color: var(--white); color: var(--white); }

.btn .icon { width: 18px; height: 18px; flex-shrink: 0; }

/* ---------------- Hero ---------------- */
.hero {
  background:
    radial-gradient(1100px 480px at 85% -10%, rgba(110, 140, 199, 0.22), transparent 60%),
    radial-gradient(900px 420px at -10% 110%, rgba(75, 106, 166, 0.12), transparent 55%),
    linear-gradient(180deg, var(--brand-lighter) 0%, var(--white) 100%);
  border-bottom: 1px solid var(--border);
  overflow: hidden;
}

.hero-inner {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 56px;
  align-items: center;
  padding: 72px 0 76px;
}

.hero h1 {
  font-size: 40px;
  line-height: 1.3;
  font-weight: 700;
  color: var(--brand-deep);
  margin-bottom: 18px;
  letter-spacing: 0.3px;
}

.hero .lead {
  font-size: 18px;
  color: var(--text-secondary);
  margin-bottom: 14px;
  max-width: 540px;
}

.hero .sub {
  font-size: 15px;
  color: var(--text-muted);
  margin-bottom: 30px;
  max-width: 540px;
}

.hero-actions { display: flex; flex-wrap: wrap; gap: 14px; margin-bottom: 26px; }

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 26px;
  font-size: 14px;
  color: var(--text-muted);
}
.hero-meta span { display: inline-flex; align-items: center; gap: 7px; }
.hero-meta svg { width: 16px; height: 16px; color: var(--brand); flex-shrink: 0; }

.hero-visual { position: relative; }

.hero-shot {
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  background: var(--white);
}

.hero-badge {
  position: absolute;
  top: -18px;
  right: -14px;
  background: var(--white);
  border: 1px solid var(--brand-border);
  border-radius: 10px;
  padding: 10px 16px;
  box-shadow: var(--shadow);
  font-size: 13px;
  font-weight: 600;
  color: var(--brand-dark);
  display: flex;
  align-items: center;
  gap: 8px;
}
.hero-badge svg { width: 18px; height: 18px; color: var(--green); }

/* ---------------- 通用区块 ---------------- */
.section { padding: 72px 0; }
.section-soft { background: var(--bg-soft); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }

.section-head { text-align: center; max-width: 720px; margin: 0 auto 48px; }
.section-head .kicker {
  display: inline-block;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 3px;
  color: var(--brand);
  text-transform: uppercase;
  margin-bottom: 12px;
}
.section-head h2 { font-size: 30px; font-weight: 700; color: var(--brand-deep); margin-bottom: 14px; }
.section-head p { color: var(--text-secondary); font-size: 16px; }

/* 网格卡片 */
.grid { display: grid; gap: 22px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }

.card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px 26px;
  transition: box-shadow 0.25s, transform 0.25s, border-color 0.25s;
}
.card:hover { box-shadow: var(--shadow-lg); transform: translateY(-3px); border-color: var(--brand-border); }

.card .card-icon {
  width: 46px;
  height: 46px;
  border-radius: 12px;
  background: var(--brand-light);
  color: var(--brand);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
}
.card .card-icon svg { width: 24px; height: 24px; }

.card h3 { font-size: 18px; font-weight: 700; color: var(--text); margin-bottom: 8px; }
.card p { font-size: 14.5px; color: var(--text-secondary); }
.card ul { margin-top: 10px; }
.card li { font-size: 14px; color: var(--text-secondary); margin-bottom: 4px; }

/* ---------------- 场景卡片 ---------------- */
.scene-card { position: relative; overflow: hidden; }
.scene-card .scene-tag {
  display: inline-block;
  font-size: 12px;
  font-weight: 700;
  color: var(--brand);
  background: var(--brand-light);
  border-radius: 20px;
  padding: 3px 12px;
  margin-bottom: 12px;
  letter-spacing: 1px;
}

/* ---------------- 数据统计条 ---------------- */
.stats-band {
  background: linear-gradient(135deg, var(--brand-dark), var(--brand));
  color: var(--white);
  padding: 44px 0;
}
.stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; text-align: center; }
.stat .num { font-size: 34px; font-weight: 700; letter-spacing: 0.5px; }
.stat .num small { font-size: 18px; font-weight: 600; margin-left: 2px; }
.stat .label { font-size: 14px; opacity: 0.85; margin-top: 4px; }

/* ---------------- 表格 ---------------- */
.table-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: var(--radius-lg); background: var(--white); }
table { width: 100%; border-collapse: collapse; font-size: 14.5px; min-width: 560px; }
thead th {
  background: var(--brand-light);
  color: var(--brand-deep);
  font-weight: 700;
  text-align: left;
  padding: 13px 18px;
  border-bottom: 1px solid var(--brand-border);
  white-space: nowrap;
}
tbody td { padding: 13px 18px; border-bottom: 1px solid var(--border); color: var(--text-secondary); vertical-align: top; }
tbody tr:last-child td { border-bottom: none; }
tbody tr:hover td { background: var(--brand-lighter); }
td .t-strong { color: var(--text); font-weight: 600; }

/* 徽章 */
.badge {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  padding: 2px 10px;
  border-radius: 20px;
  background: var(--brand-light);
  color: var(--brand-dark);
  white-space: nowrap;
}
.badge-green { background: #E8F5EE; color: var(--green); }
.badge-gray { background: #EEF1F5; color: var(--text-muted); }

/* ---------------- 步骤 ---------------- */
.steps { display: grid; grid-template-columns: repeat(4, 1fr); gap: 22px; counter-reset: step; }
.step { position: relative; padding: 26px 22px; background: var(--white); border: 1px solid var(--border); border-radius: var(--radius-lg); }
.step .step-no {
  counter-increment: step;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--brand);
  color: var(--white);
  font-size: 17px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 14px;
}
.step .step-no::before { content: counter(step); }
.step h3 { font-size: 17px; font-weight: 700; margin-bottom: 6px; }
.step p { font-size: 14px; color: var(--text-secondary); }

/* ---------------- FAQ ---------------- */
.faq-list { max-width: 820px; margin: 0 auto; }
details.faq {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0 22px;
  margin-bottom: 12px;
  transition: border-color 0.2s;
}
details.faq[open] { border-color: var(--brand-border); box-shadow: var(--shadow); }
details.faq summary {
  cursor: pointer;
  list-style: none;
  font-size: 16px;
  font-weight: 600;
  color: var(--text);
  padding: 16px 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
details.faq summary::-webkit-details-marker { display: none; }
details.faq summary::after {
  content: "";
  width: 10px;
  height: 10px;
  border-right: 2px solid var(--text-muted);
  border-bottom: 2px solid var(--text-muted);
  transform: rotate(45deg);
  transition: transform 0.25s;
  flex-shrink: 0;
  margin-top: -4px;
}
details.faq[open] summary::after { transform: rotate(-135deg); margin-top: 4px; }
details.faq .faq-body { padding: 0 0 18px; color: var(--text-secondary); font-size: 15px; }
details.faq .faq-body p + p { margin-top: 8px; }
details.faq .faq-body code { font-family: var(--font-mono); font-size: 13px; background: var(--brand-light); color: var(--brand-dark); padding: 1px 6px; border-radius: 4px; }

/* ---------------- 下载页 ---------------- */
.dl-platform { scroll-margin-top: 90px; }
.dl-card {
  display: grid;
  grid-template-columns: 56px 1fr auto;
  gap: 20px;
  align-items: center;
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 22px 26px;
  margin-bottom: 16px;
  transition: box-shadow 0.25s, border-color 0.25s;
}
.dl-card:hover { box-shadow: var(--shadow-lg); border-color: var(--brand-border); }
.dl-card .os-icon {
  width: 56px;
  height: 56px;
  border-radius: 14px;
  background: var(--brand-light);
  color: var(--brand);
  display: flex;
  align-items: center;
  justify-content: center;
}
.dl-card .os-icon svg { width: 30px; height: 30px; }
.dl-card h3 { font-size: 18px; font-weight: 700; margin-bottom: 2px; }
.dl-card .dl-note { font-size: 13.5px; color: var(--text-muted); }
.dl-card .dl-meta { font-size: 13px; color: var(--text-muted); margin-top: 4px; display: flex; flex-wrap: wrap; gap: 6px 16px; }

.note-box {
  background: var(--brand-lighter);
  border: 1px solid var(--brand-border);
  border-left: 4px solid var(--brand);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 16px 20px;
  font-size: 14.5px;
  color: var(--text-secondary);
  margin: 22px 0;
}
.note-box strong { color: var(--brand-dark); }

/* ---------------- 页脚 ---------------- */
.site-footer { background: var(--brand-deep); color: #C4CEDF; margin-top: 72px; }
.footer-grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr 1fr;
  gap: 40px;
  padding: 56px 0 40px;
}
.footer-brand img { height: 32px; margin-bottom: 14px; }
.footer-brand p { font-size: 14px; line-height: 1.8; opacity: 0.82; max-width: 340px; }
.site-footer h4 { color: var(--white); font-size: 15px; font-weight: 600; margin-bottom: 14px; letter-spacing: 0.5px; }
.footer-links { list-style: none; padding: 0; }
.footer-links li { margin-bottom: 9px; }
.footer-links a { color: #C4CEDF; font-size: 14px; }
.footer-links a:hover { color: var(--white); }
.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  padding: 20px 0;
  font-size: 13px;
  color: #92A0BB;
  display: flex;
  flex-wrap: wrap;
  gap: 10px 24px;
  align-items: center;
  justify-content: space-between;
}

/* ---------------- 下载弹窗 ---------------- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(26, 35, 52, 0.55);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  z-index: 999;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.25s, visibility 0.25s;
}
.modal-overlay.open { opacity: 1; visibility: visible;   left: 0;
  right: 0;
  top: 0;
  bottom: 0;}
button { outline: none } 
.modal {
  background: var(--white);
  border-radius: 18px;
  width: 100%;
  max-width: 640px;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: 0 24px 70px rgba(26, 35, 52, 0.35);
  transform: translateY(16px) scale(0.97);
  transition: transform 0.28s;
}
.modal-overlay.open .modal { transform: translateY(0) scale(1); }

.modal-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 26px 16px;
  border-bottom: 1px solid var(--border);
}
.modal-head h3 { font-size: 19px; font-weight: 700; color: var(--brand-deep); }
.modal-head .ver { font-size: 13px; color: var(--text-muted); font-weight: 400; margin-left: 8px; }
.modal-close {
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
  border-radius: 8px;
  color: var(--text-muted);
  display: flex;
  transition: background 0.2s, color 0.2s;
}
.modal-close:hover { background: #EEF1F5; color: var(--text); }
.modal-close svg { width: 20px; height: 20px; }

.modal-body { padding: 24px 26px 26px; }
.modal-body .modal-tip {
  font-size: 14px;
  color: var(--text-secondary);
  text-align: center;
  margin-bottom: 22px;
}

.qr-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.qr-item {
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 22px 16px 18px;
  text-align: center;
  background: var(--bg-soft);
  transition: border-color 0.2s, box-shadow 0.2s;
}
.qr-item:hover { border-color: var(--brand); box-shadow: var(--shadow); }
.qr-item img {
  width: 168px;
  height: 168px;
  margin: 0 auto 12px;
  border-radius: 8px;
  background: var(--white);
  padding: 8px;
  border: 1px solid var(--border);
}
.qr-item .qr-title { font-size: 15px; font-weight: 600; color: var(--text); margin-bottom: 4px; }
.qr-item .qr-sub { font-size: 12.5px; color: var(--text-muted); }

.modal-foot {
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px dashed var(--border);
  font-size: 12.5px;
  color: var(--text-muted);
  text-align: center;
  line-height: 1.7;
}

/* ---------------- 面包屑 ---------------- */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-size: 13.5px;
  color: var(--text-muted);
  padding: 20px 0 0;
}
.breadcrumb a { color: var(--text-muted); }
.breadcrumb a:hover { color: var(--brand); }
.breadcrumb .sep { color: #B7C0CF; }
.breadcrumb .cur { color: var(--text); font-weight: 500; }

/* ---------------- 页面横幅（内页） ---------------- */
.page-hero {
  background:
    radial-gradient(900px 380px at 90% -20%, rgba(110, 140, 199, 0.20), transparent 60%),
    linear-gradient(180deg, var(--brand-lighter), var(--white));
  border-bottom: 1px solid var(--border);
  padding: 44px 0 48px;
}
.page-hero h1 { font-size: 32px; font-weight: 700; color: var(--brand-deep); margin-bottom: 10px; }
.page-hero p { color: var(--text-secondary); max-width: 760px; font-size: 16px; }

/* 正文内容块 */
.prose h2 {
  font-size: 24px;
  font-weight: 700;
  color: var(--brand-deep);
  margin: 44px 0 16px;
  padding-left: 14px;
  border-left: 4px solid var(--brand);
}
.prose h3 { font-size: 18px; font-weight: 700; color: var(--text); margin: 28px 0 10px; }
.prose p { color: var(--text-secondary); margin-bottom: 12px; }
.prose ul, .prose ol { color: var(--text-secondary); margin-bottom: 14px; }
.prose li { margin-bottom: 6px; }
.prose code { font-family: var(--font-mono); font-size: 13px; background: var(--brand-light); color: var(--brand-dark); padding: 1px 6px; border-radius: 4px; }

/* CTA 横幅 */
.cta-band { background: linear-gradient(135deg, var(--brand-dark), var(--brand)); border-radius: var(--radius-lg); padding: 46px 48px; color: var(--white); display: flex; align-items: center; justify-content: space-between; gap: 28px; flex-wrap: wrap; }
.cta-band h2 { font-size: 24px; font-weight: 700; margin-bottom: 6px; }
.cta-band p { opacity: 0.88; font-size: 15px; }

/* ---------------- 响应式 ---------------- */
@media (max-width: 960px) {
  .hero-inner { grid-template-columns: 1fr; padding: 52px 0 56px; }
  .hero h1 { font-size: 32px; }
  .grid-3, .grid-4, .steps, .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
  .cta-band { padding: 36px 30px; }
}

@media (max-width: 640px) {
  .grid-2, .grid-3, .grid-4, .steps, .stats-grid { grid-template-columns: 1fr; }
  .nav-links, .nav-cta { display: none; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    align-items: stretch;
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    background: var(--white);
    border-bottom: 1px solid var(--border);
    padding: 12px 24px 18px;
    gap: 4px;
    box-shadow: var(--shadow-lg);
  }
  .nav-toggle { display: block; }
  .hero h1 { font-size: 27px; }
  .section { padding: 52px 0; }
  .section-head h2 { font-size: 24px; }
  .page-hero h1 { font-size: 26px; }
  .dl-card { grid-template-columns: 1fr; text-align: center; }
  .dl-card .os-icon { margin: 0 auto; }
  .qr-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .footer-bottom { justify-content: flex-start; }
}