/* ============================================================
   严选AI 设计系统 —— 暖白纸底 + 墨色文字 + 靛蓝强调
   与 aixujue.cn 视觉统一
   ============================================================ */
:root {
  color-scheme: light;

  --paper: #f8f7f4;
  --paper-soft: #f1efea;
  --surface: #ffffff;
  --surface-tint: #f6f7fb;

  --text: #1c2027;
  --text-soft: #4b535f;
  --text-dim: #616a75;
  --text-faint: #8a929b;

  --line: #e5e1d8;
  --line-soft: #eeeae2;
  --line-strong: #d6d0c4;

  --accent: #2f52c8;
  --accent-hover: #2440a6;
  --accent-soft: #eef1fd;
  --accent-2: #4a6cf0;
  --accent-warm: #9c5c1c;
  --accent-green: #2f7a5a;

  --radius-lg: 18px;
  --radius: 14px;
  --radius-sm: 9px;
  --radius-pill: 999px;

  --maxw: 1160px;
  --maxw-prose: 760px;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --font-serif: "Songti SC", "SimSun", "Noto Serif SC", Georgia, serif;

  --shadow-xs: 0 1px 2px rgba(28, 32, 39, 0.05);
  --shadow: 0 1px 2px rgba(28, 32, 39, 0.04), 0 10px 26px -16px rgba(28, 32, 39, 0.2);
  --shadow-hover: 0 2px 6px rgba(28, 32, 39, 0.06), 0 20px 40px -18px rgba(28, 32, 39, 0.26);

  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --header-h: 63px;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; scroll-padding-top: 92px; }
html, body { overflow-x: clip; }

body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  background-color: var(--paper);
  background-image:
    radial-gradient(1000px 420px at 6% -12%, rgba(74, 108, 240, 0.055), transparent 62%),
    radial-gradient(880px 400px at 98% -6%, rgba(184, 114, 42, 0.05), transparent 60%);
  background-attachment: fixed;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.72;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: var(--accent); text-decoration: none; transition: color 0.15s var(--ease); }
a:hover { color: var(--accent-hover); }

/* ============================================================ 页头 */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--header-h);
  background: rgba(248, 247, 244, 0.88);
  backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--line-soft);
}
.header-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.brand { display: inline-flex; align-items: center; gap: 10px; color: var(--text); font-weight: 700; }
.brand:hover { color: var(--text); }
.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px; height: 34px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #fff;
  font-size: 18px;
  font-weight: 800;
  box-shadow: var(--shadow-xs);
}
.brand-name { font-size: 17px; letter-spacing: 0.5px; }
.site-nav { display: flex; gap: 8px; align-items: center; }
.site-nav a {
  color: var(--text-soft);
  padding: 7px 14px;
  border-radius: var(--radius-pill);
  font-size: 15px;
  font-weight: 500;
}
.site-nav a:hover { background: var(--surface); color: var(--text); }
.site-nav a[aria-current="page"] { color: var(--accent); background: var(--accent-soft); }

/* ============================================================ 布局 */
.wrap {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 32px 24px 80px;
  position: relative;
  z-index: 1;
}
.block { margin-top: 64px; }
.section-head { margin-bottom: 28px; }
.section-title {
  margin: 0 0 6px;
  font-size: 26px;
  font-weight: 700;
  letter-spacing: -0.01em;
}
.section-sub { margin: 0; color: var(--text-dim); font-size: 15px; }

/* ============================================================ Hero */
.hero { margin-top: 24px; }
.hero-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 48px;
  align-items: center;
}
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-pill);
  color: var(--text-soft);
  font-size: 13px;
  font-weight: 500;
  box-shadow: var(--shadow-xs);
}
.hero-copy h1 {
  margin: 20px 0 16px;
  font-size: clamp(30px, 4.5vw, 46px);
  line-height: 1.18;
  font-weight: 800;
  letter-spacing: -0.02em;
}
.hero-lead {
  margin: 0 0 28px;
  font-size: 17px;
  line-height: 1.75;
  color: var(--text-soft);
  max-width: 36em;
}
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 12px 24px;
  border-radius: var(--radius-pill);
  font-size: 15px;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.18s var(--ease);
}
.btn-primary { background: var(--accent); color: #fff; box-shadow: var(--shadow); }
.btn-primary:hover { background: var(--accent-hover); color: #fff; transform: translateY(-1px); box-shadow: var(--shadow-hover); }
.btn-ghost { background: var(--surface); border-color: var(--line); color: var(--text); }
.btn-ghost:hover { border-color: var(--line-strong); color: var(--text); transform: translateY(-1px); }

.hero-links { list-style: none; margin: 0; padding: 0; display: grid; gap: 12px; }
.hero-links li a {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 18px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: var(--text);
  box-shadow: var(--shadow-xs);
  transition: all 0.18s var(--ease);
}
.hero-links li a:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow);
  transform: translateY(-2px);
  color: var(--text);
}
.hl-icon { font-size: 26px; line-height: 1; }
.hl-text { display: flex; flex-direction: column; }
.hl-text strong { font-size: 15px; font-weight: 600; }
.hl-text em { font-style: normal; font-size: 13px; color: var(--text-dim); }

/* ============================================================ 数据带 */
.factbar {
  margin-top: 56px;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow);
}
.factbar > div {
  padding: 24px 20px;
  border-right: 1px solid var(--line-soft);
  text-align: center;
}
.factbar > div:last-child { border-right: none; }
.factbar strong {
  display: block;
  font-size: 18px;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 4px;
}
.factbar span { font-size: 13px; color: var(--text-dim); }

/* ============================================================ 分类卡片 */
.grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}
.tile {
  display: block;
  padding: 28px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  color: var(--text);
  box-shadow: var(--shadow-xs);
  transition: all 0.18s var(--ease);
}
.tile:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow-hover);
  transform: translateY(-3px);
  color: var(--text);
}
.tile-icon { font-size: 34px; line-height: 1; display: block; margin-bottom: 16px; }
.tile h3 { margin: 0 0 10px; font-size: 19px; font-weight: 700; }
.tile p { margin: 0 0 16px; font-size: 15px; color: var(--text-soft); line-height: 1.68; }
.tile-count { font-size: 14px; font-weight: 600; color: var(--accent); }

/* ============================================================ 严选标准 */
.standards { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }
.standards li {
  display: flex;
  gap: 18px;
  padding: 24px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow-xs);
}
.std-num {
  flex-shrink: 0;
  font-size: 22px;
  font-weight: 800;
  color: var(--accent);
  font-variant-numeric: tabular-nums;
  line-height: 1.1;
}
.standards h3 { margin: 0 0 6px; font-size: 17px; font-weight: 700; }
.standards p { margin: 0; font-size: 14px; color: var(--text-soft); line-height: 1.65; }

/* ============================================================ 占位卡 */
.placeholder-card {
  text-align: center;
  padding: 56px 32px;
  background: var(--surface);
  border: 1px dashed var(--line-strong);
  border-radius: var(--radius-lg);
}
.ph-icon { font-size: 48px; margin-bottom: 16px; }
.placeholder-card h3 { margin: 0 0 12px; font-size: 20px; font-weight: 700; }
.placeholder-card p { margin: 0 auto; max-width: 40em; color: var(--text-soft); font-size: 15px; line-height: 1.7; }
.ph-hint { margin-top: 12px !important; font-size: 14px !important; color: var(--text-dim) !important; }

/* ============================================================ 关于页（prose） */
.prose {
  max-width: var(--maxw-prose);
  margin: 40px auto 0;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 48px;
  box-shadow: var(--shadow);
}
.eyebrow {
  display: inline-block;
  font-size: 13px;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 8px;
}
.prose h1 { margin: 0 0 24px; font-size: 32px; font-weight: 800; letter-spacing: -0.02em; }
.prose h2 { margin: 36px 0 14px; font-size: 22px; font-weight: 700; }
.prose p { margin: 0 0 16px; color: var(--text-soft); line-height: 1.8; }
.prose strong { color: var(--text); font-weight: 600; }
.prose ul, .prose ol { margin: 0 0 20px; padding-left: 22px; color: var(--text-soft); line-height: 1.85; }
.prose li { margin-bottom: 8px; }
.prose li strong { color: var(--text); }
.facts { display: grid; grid-template-columns: max-content 1fr; gap: 8px 20px; margin: 0 0 24px; }
.facts dt { color: var(--text-dim); font-size: 14px; }
.facts dd { margin: 0; color: var(--text); font-weight: 500; }
.back-home { margin-top: 32px; padding-top: 24px; border-top: 1px solid var(--line-soft); }

/* ============================================================ 页脚 */
.site-footer {
  border-top: 1px solid var(--line);
  background: var(--paper-soft);
  padding: 40px 0;
  position: relative;
  z-index: 1;
}
.footer-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: 32px;
  align-items: center;
}
.footer-brand { display: flex; align-items: center; gap: 12px; }
.footer-brand div { display: flex; flex-direction: column; }
.footer-brand strong { font-size: 15px; color: var(--text); }
.footer-brand span { font-size: 13px; color: var(--text-dim); }
.footer-nav { display: flex; gap: 20px; justify-content: center; }
.footer-nav a { color: var(--text-soft); font-size: 14px; }
.footer-beian { text-align: right; }
.footer-beian p { margin: 0; font-size: 14px; }
.footer-beian a { color: var(--text-soft); }
.footer-beian .small { font-size: 12px; color: var(--text-faint); margin-top: 4px; }

/* ============================================================ 响应式 */
@media (max-width: 880px) {
  .hero-grid { grid-template-columns: 1fr; gap: 32px; }
  .factbar { grid-template-columns: repeat(2, 1fr); }
  .factbar > div:nth-child(2) { border-right: none; }
  .factbar > div:nth-child(1), .factbar > div:nth-child(2) { border-bottom: 1px solid var(--line-soft); }
  .grid, .standards { grid-template-columns: 1fr; }
  .footer-inner { grid-template-columns: 1fr; gap: 20px; text-align: center; }
  .footer-nav { justify-content: center; }
  .footer-beian { text-align: center; }
  .prose { padding: 32px 24px; margin-top: 24px; }
  .wrap { padding: 20px 16px 56px; }
}
@media (max-width: 520px) {
  .site-nav a { padding: 7px 10px; font-size: 14px; }
  .brand-name { display: none; }
  .hero-actions .btn { flex: 1; justify-content: center; }
}