/* ===========================================================================
   晓渡 AI · Shared Stylesheet
   xduai.com brand system v1.0
   =========================================================================== */

:root{
  --ink: #14252A;
  --ink-soft: #2A3A3F;
  --ink-faint: #5A6669;
  --jade: #4A7C7E;
  --jade-light: #7AAEAB;
  --paper: #FAF7F0;
  --mist: #E8EDED;
  --warm-mist: #F0EDE4;
  --pop: #FF6B47;
  --pop-soft: #FFE5DD;
  --gold: #E8B547;

  --serif-zh: "Noto Serif SC", "Source Han Serif", "STSong", "Songti SC", serif;
  --sans-zh: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  --serif-en: "Fraunces", "Cormorant", serif;
  --mono: "JetBrains Mono", "SF Mono", monospace;

  --line: rgba(20, 37, 42, 0.08);
  --line-strong: rgba(20, 37, 42, 0.15);
  --line-bold: rgba(20, 37, 42, 0.3);
}

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

html{ scroll-behavior: smooth; overflow-x: hidden; }
body{
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans-zh);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

a{ color: inherit; text-decoration: none; }
img{ max-width: 100%; display: block; }

.container{
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 32px;
}
.container-narrow{
  max-width: 820px;
  margin: 0 auto;
  padding: 0 32px;
}

/* ===== NAV ===== */
.nav{
  position: sticky;
  top: 0;
  background: rgba(250, 247, 240, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 0.5px solid var(--line);
  z-index: 100;
}
.nav-inner{
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 0;
}
.brand{ display: flex; align-items: center; gap: 14px; }
.brand-mark{ width: 36px; height: 36px; flex-shrink: 0; }
.brand-text{
  display: flex;
  flex-direction: column;
  border-left: 0.5px solid var(--line-strong);
  padding-left: 14px;
}
.brand-cn{
  font-family: var(--serif-zh);
  font-size: 18px;
  font-weight: 500;
  letter-spacing: 0.05em;
}
.brand-en{
  font-family: var(--mono);
  font-size: 9px;
  letter-spacing: 0.25em;
  color: var(--jade);
  margin-top: 2px;
}
.nav-links{
  display: flex;
  gap: 36px;
  font-size: 14px;
  color: var(--ink-soft);
}
.nav-links a{ position: relative; transition: color 0.2s; }
.nav-links a:hover, .nav-links a.active{ color: var(--pop); }
.nav-cta{
  padding: 9px 22px;
  background: var(--ink);
  color: var(--paper);
  font-size: 13px;
  letter-spacing: 0.05em;
  border-radius: 4px;
  transition: all 0.25s;
}
.nav-cta:hover{ background: var(--pop); transform: translateY(-1px); }
@media(max-width: 768px){ .nav-links{ display: none; } }

/* ===== Buttons ===== */
.btn{
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 30px;
  font-size: 14px;
  letter-spacing: 0.05em;
  border-radius: 4px;
  transition: all 0.25s ease;
  cursor: pointer;
  border: 0.5px solid transparent;
  font-family: inherit;
}
.btn-primary{ background: var(--ink); color: var(--paper); }
.btn-primary:hover{
  background: var(--pop);
  transform: translate(-2px,-2px);
  box-shadow: 4px 4px 0 var(--ink);
}
.btn-secondary{
  background: transparent;
  color: var(--ink);
  border-color: var(--line-strong);
}
.btn-secondary:hover{
  border-color: var(--ink);
  background: var(--mist);
}
.btn-pop{ background: var(--pop); color: var(--paper); }
.btn-pop:hover{ background: var(--ink); }

/* ===== Section ===== */
section{ padding: 100px 0; position: relative; }
.section-eyebrow{
  font-family: var(--mono);
  font-size: 11px;
  color: var(--jade);
  letter-spacing: 0.25em;
  margin-bottom: 14px;
}
.section-title{
  font-family: var(--serif-zh);
  font-size: clamp(32px, 4vw, 48px);
  font-weight: 500;
  letter-spacing: 0.03em;
  line-height: 1.3;
  margin-bottom: 20px;
  max-width: 820px;
}
.section-title em{
  font-family: var(--serif-en);
  font-style: italic;
  font-weight: 300;
  color: var(--jade);
}
.section-lead{
  font-family: var(--serif-zh);
  font-size: 17px;
  color: var(--ink-soft);
  line-height: 1.85;
  max-width: 640px;
  margin-bottom: 64px;
}

/* ===== 内页 Hero ===== */
.page-hero{
  padding: 100px 0 60px;
  border-bottom: 0.5px solid var(--line);
}
.page-hero .section-eyebrow{ margin-bottom: 24px; }
.page-hero h1{
  font-family: var(--serif-zh);
  font-size: clamp(40px, 5vw, 64px);
  font-weight: 500;
  letter-spacing: 0.03em;
  line-height: 1.2;
  margin-bottom: 24px;
}
.page-hero h1 em{
  font-family: var(--serif-en);
  font-style: italic;
  font-weight: 300;
  color: var(--jade);
}
.page-hero-sub{
  font-family: var(--serif-zh);
  font-size: 18px;
  color: var(--ink-soft);
  max-width: 680px;
  line-height: 1.85;
}

/* ===== Footer ===== */
.footer{
  background: var(--ink);
  color: var(--paper);
  padding: 80px 0 40px;
}
.footer-grid{
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 60px;
  margin-bottom: 64px;
}
@media(max-width: 768px){ .footer-grid{ grid-template-columns: 1fr 1fr; gap: 40px; } }
.footer-brand{ display: flex; flex-direction: column; gap: 20px; }
.footer-brand-title{
  display: flex; align-items: center; gap: 14px;
}
.footer-brand-text{
  font-family: var(--serif-zh);
  color: var(--paper);
  opacity: 0.85;
  font-size: 14px;
  line-height: 1.85;
  max-width: 320px;
}
.footer-col h4{
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.25em;
  color: var(--jade-light);
  margin-bottom: 20px;
  font-weight: 500;
}
.footer-col a{
  display: block;
  font-size: 13px;
  color: var(--paper);
  opacity: 0.7;
  padding: 6px 0;
  transition: opacity 0.2s;
}
.footer-col a:hover{ opacity: 1; color: var(--pop); }
.footer-bottom{
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 32px;
  border-top: 0.5px solid rgba(255,255,255,0.08);
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.15em;
  color: rgba(250, 247, 240, 0.5);
  flex-wrap: wrap;
  gap: 16px;
}
.footer-seal{ display: flex; align-items: center; gap: 12px; }
.footer-seal-stamp{
  display: inline-block;
  background: var(--pop);
  color: var(--paper);
  padding: 4px 12px;
  border-radius: 2px;
  font-family: 'STKaiti', serif;
  font-size: 11px;
  letter-spacing: 0.4em;
  font-weight: 500;
}

/* ===== 通用 Card ===== */
.card{
  background: var(--paper);
  border: 0.5px solid var(--line);
  padding: 32px;
  border-radius: 4px;
  transition: all 0.25s;
}
.card:hover{ border-color: var(--line-bold); }
.card-elev{
  background: var(--paper);
  border: 0.5px solid var(--line-strong);
  padding: 40px 36px;
  border-radius: 4px;
}

/* ===== Form 控件 ===== */
.form-field{ margin-bottom: 24px; }
.form-label{
  display: block;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--jade);
  margin-bottom: 10px;
  text-transform: uppercase;
}
.form-input{
  width: 100%;
  padding: 14px 18px;
  background: var(--paper);
  border: 0.5px solid var(--line-strong);
  border-radius: 4px;
  font-family: var(--sans-zh);
  font-size: 15px;
  color: var(--ink);
  transition: border-color 0.2s;
}
.form-input:focus{ outline: none; border-color: var(--ink); }
.form-input::placeholder{ color: var(--ink-faint); }

/* ===== Tag / Badge ===== */
.tag{
  display: inline-block;
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.2em;
  padding: 4px 10px;
  border-radius: 2px;
  text-transform: uppercase;
}
.tag-jade{ background: var(--mist); color: var(--jade); }
.tag-pop{ background: var(--pop-soft); color: var(--pop); }
.tag-ink{ background: var(--ink); color: var(--paper); }

/* ===== 表格 ===== */
.kv-table{
  width: 100%;
  border-collapse: collapse;
}
.kv-table tr{ border-bottom: 0.5px dashed var(--line); }
.kv-table tr:last-child{ border-bottom: none; }
.kv-table td{
  padding: 14px 0;
  font-size: 14px;
}
.kv-table td:first-child{
  color: var(--ink-faint);
  width: 40%;
}
.kv-table td:last-child{
  color: var(--ink);
  font-family: var(--mono);
  text-align: right;
}

/* ===== 进场动画 ===== */
.fade-up{
  opacity: 0;
  transform: translateY(20px);
  animation: fadeUp 0.9s ease forwards;
}
.fade-up:nth-child(1){ animation-delay: 0.1s; }
.fade-up:nth-child(2){ animation-delay: 0.25s; }
.fade-up:nth-child(3){ animation-delay: 0.4s; }
.fade-up:nth-child(4){ animation-delay: 0.55s; }
@keyframes fadeUp{
  to{ opacity: 1; transform: translateY(0); }
}

/* ===== 长文档样式 ===== */
.prose{
  font-family: var(--serif-zh);
  font-size: 16px;
  line-height: 1.95;
  color: var(--ink-soft);
}
.prose h2{
  font-family: var(--serif-zh);
  font-size: 28px;
  font-weight: 500;
  color: var(--ink);
  margin: 56px 0 20px;
  letter-spacing: 0.02em;
}
.prose h3{
  font-family: var(--serif-zh);
  font-size: 20px;
  font-weight: 500;
  color: var(--ink);
  margin: 40px 0 14px;
}
.prose p{ margin-bottom: 18px; }
.prose ul, .prose ol{
  margin: 0 0 24px 24px;
}
.prose li{ margin-bottom: 8px; }
.prose strong{ color: var(--ink); font-weight: 500; }
.prose a{ color: var(--pop); border-bottom: 0.5px solid var(--pop); }
.prose code{
  background: var(--mist);
  padding: 2px 8px;
  font-family: var(--mono);
  font-size: 13px;
  border-radius: 2px;
}
.prose pre{
  background: var(--ink);
  color: var(--paper);
  padding: 20px 24px;
  border-radius: 4px;
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.7;
  margin: 24px 0;
  overflow-x: auto;
}
.prose pre code{ background: transparent; padding: 0; color: inherit; font-size: inherit; }
.prose blockquote{
  border-left: 2px solid var(--pop);
  padding-left: 24px;
  margin: 24px 0;
  color: var(--ink-faint);
  font-style: italic;
}

/* ===== 工具类 ===== */
.text-center{ text-align: center; }
.mt-0{ margin-top: 0 !important; }
.mt-2{ margin-top: 16px; }
.mt-4{ margin-top: 32px; }
.mt-6{ margin-top: 48px; }
.mt-8{ margin-top: 64px; }
.mb-0{ margin-bottom: 0 !important; }
.mb-2{ margin-bottom: 16px; }
.mb-4{ margin-bottom: 32px; }
.mb-6{ margin-bottom: 48px; }
.mb-8{ margin-bottom: 64px; }