/* =============================================
   AI导航 - 帮助中心样式
   ============================================= */
:root {
  --hc-bg: #ffffff;
  --hc-bg2: #f8f9fc;
  --hc-card: #ffffff;
  --hc-border: #e8ecf4;
  --hc-text: #1a202c;
  --hc-text2: #5a657f;
  --hc-text3: #8b95a8;
  --hc-accent: #5c6bc0;
  --hc-accent2: #7986cb;
  --hc-green: #34a853;
  --hc-orange: #f59e0b;
  --hc-red: #ef4444;
  --hc-radius: 12px;
  --hc-shadow: 0 1px 3px rgba(0,0,0,0.06), 0 4px 16px rgba(92,107,192,0.08);
}
@media (prefers-color-scheme: dark) {
  :root {
    --hc-bg: #111827;
    --hc-bg2: #1a2035;
    --hc-card: #1e2740;
    --hc-border: #2d3654;
    --hc-text: #e8ecf4;
    --hc-text2: #9ca3bf;
    --hc-text3: #636d88;
    --hc-accent: #7986cb;
    --hc-accent2: #9ca3d6;
  }
}

* { margin:0; padding:0; box-sizing:border-box; }
html { font-size:16px; scroll-behavior:smooth; }

body {
  font-family: -apple-system,BlinkMacSystemFont,'Segoe UI','PingFang SC','Microsoft YaHei',sans-serif;
  background: var(--hc-bg); color: var(--hc-text);
  line-height: 1.8; min-height:100vh;
}

a { color: var(--hc-accent); text-decoration:none; transition:color 0.2s; }
a:hover { color: var(--hc-accent2); text-decoration:underline; }

/* Header */
.hc-header {
  background: var(--hc-card);
  border-bottom: 1px solid var(--hc-border);
  position: sticky; top:0; z-index:100;
  backdrop-filter: blur(10px);
}
.hc-header-inner {
  max-width:1100px; margin:0 auto; padding:16px 24px;
  display:flex; align-items:center; justify-content:space-between;
}
.hc-logo {
  display:flex; align-items:center; gap:10px;
  font-size:18px; font-weight:700; color:var(--hc-text);
}
.hc-logo img { width:32px; height:32px; border-radius:8px; }
.hc-logo span { color:var(--hc-accent); }
.hc-nav { display:flex; gap:20px; flex-wrap:wrap; }
.hc-nav a {
  font-size:14px; color:var(--hc-text2);
  padding:4px 0; border-bottom:2px solid transparent;
  transition:border-color 0.2s, color 0.2s;
}
.hc-nav a:hover,
.hc-nav a.active { color:var(--hc-accent); border-bottom-color:var(--hc-accent); text-decoration:none; }

/* Breadcrumb */
.hc-breadcrumb {
  max-width:1100px; margin:0 auto; padding:14px 24px 0;
  font-size:13px; color:var(--hc-text3);
}
.hc-breadcrumb a { color:var(--hc-text3); }
.hc-breadcrumb a:hover { color:var(--hc-accent); }

/* Main */
.hc-main {
  max-width:1100px; margin:0 auto; padding:24px;
}

/* Hero section for index */
.hc-hero {
  background: linear-gradient(135deg,#667eea 0%,#764ba2 50%,#f093fb 100%);
  border-radius:20px; padding:48px 40px; margin-bottom:32px;
  color:#fff; position:relative; overflow:hidden;
}
.hc-hero::before {
  content:''; position:absolute; top:-40%; right:-10%;
  width:300px; height:300px; border-radius:50%;
  background:rgba(255,255,255,0.1);
}
.hc-hero h1 { font-size:clamp(26px,4vw,38px); font-weight:800; line-height:1.3; margin-bottom:14px; }
.hc-hero p { font-size:16px; opacity:0.9; max-width:600px; line-height:1.7; }
.hc-hero .hc-stats { display:flex; gap:28px; margin-top:24px; }
.hc-hero .stat-item .num { font-size:28px; font-weight:800; }
.hc-hero .stat-item .label { font-size:13px; opacity:0.8; }

/* Category grid on index */
.hc-cat-grid {
  display:grid; grid-template-columns:repeat(auto-fill,minmax(240px,1fr));
  gap:16px; margin-bottom:40px;
}
.hc-cat-card {
  background:var(--hc-card); border:1px solid var(--hc-border);
  border-radius:var(--hc-radius); padding:22px;
  transition:transform 0.25s, box-shadow 0.25s, border-color 0.25s;
}
.hc-cat-card:hover {
  transform:translateY(-3px); box-shadow:var(--hc-shadow);
  border-color:var(--hc-accent);
}
.hc-cat-icon { font-size:28px; margin-bottom:10px; }
.hc-cat-title { font-size:17px; font-weight:700; margin-bottom:6px; }
.hc-cat-desc { font-size:13px; color:var(--hc-text2); line-height:1.6; margin-bottom:12px; }
.hc-cat-count { font-size:12px; color:var(--hc-accent); font-weight:600; }
.hc-cat-link { display:inline-block; font-size:13px; font-weight:600; color:var(--hc-accent); margin-top:8px; }
.hc-cat-link::after { content:' →'; margin-left:4px; }

/* Article layout */
.hc-article { display:grid; grid-template-columns:1fr 260px; gap:32px; }
.hc-content { min-width:0; }
.hc-sidebar { position:relative; }

/* Article styles */
.hc-content h1 {
  font-size:clamp(24px,3vw,32px); font-weight:800; line-height:1.35;
  margin-bottom:16px; color:var(--hc-text);
}
.hc-content h2 {
  font-size:22px; font-weight:700; margin:36px 0 14px;
  padding-bottom:10px; border-bottom:2px solid var(--hc-border); color:var(--hc-text);
}
.hc-content h3 { font-size:18px; font-weight:600; margin:28px 0 10px; color:var(--hc-text); }
.hc-content p { margin-bottom:16px; font-size:15px; color:var(--hc-text2); line-height:1.85; }
.hc-content strong { color:var(--hc-text); font-weight:600; }
.hc-content ul, .hc-content ol { padding-left:22px; margin-bottom:16px; }
.hc-content li { margin-bottom:8px; font-size:15px; color:var(--hc-text2); line-height:1.75; }
.hc-content blockquote {
  border-left:4px solid var(--hc-accent); background:var(--hc-bg2);
  padding:16px 20px; margin:20px 0; border-radius:0 8px 8px 0;
  font-style:italic; color:var(--hc-text2);
}
.hc-content table {
  width:100%; border-collapse:collapse; margin:20px 0;
  font-size:14px;
}
.hc-content th {
  background:var(--hc-bg2); padding:10px 14px;
  text-align:left; font-weight:600; border:1px solid var(--hc-border);
}
.hc-content td { padding:10px 14px; border:1px solid var(--hc-border); color:var(--hc-text2); }
.hc-content code {
  background:var(--hc-bg2); padding:2px 7px; border-radius:4px;
  font-size:13px; font-family:'Fira Code',monospace; color:var(--hc-accent);
}

/* Info boxes */
.hc-tip {
  background:linear-gradient(135deg,#eff6ff,#dbeafe); border:1px solid #93c5fd;
  border-radius:10px; padding:16px 20px; margin:20px 0;
  font-size:14px; color:#1e40af; line-height:1.7;
}
.hc-warning {
  background:linear-gradient(135deg,#fffbeb,#fef3c7); border:1px solid #fbbf24;
  border-radius:10px; padding:16px 20px; margin:20px 0;
  font-size:14px; color:#92400e; line-height:1.7;
}

/* TOC sidebar */
.toc-box {
  background:var(--hc-card); border:1px solid var(--hc-border);
  border-radius:var(--hc-radius); padding:20px;
  position:sticky; top:80px;
}
.toc-box h3 { font-size:15px; font-weight:700; margin-bottom:12px; }
.toc-list { list-style:none; padding:0; }
.toc-list li { margin-bottom:6px; }
.toc-list a {
  font-size:13px; color:var(--hc-text2); display:block;
  padding:4px 0; padding-left:12px; border-left:2px solid transparent;
  transition:all 0.2s;
}
.toc-list a:hover { color:var(--hc-accent); border-left-color:var(--hc-accent); text-decoration:none; }

/* Category list in sidebar */
.cat-nav-list { list-style:none; padding:0; }
.cat-nav-list li { margin-bottom:2px; }
.cat-nav-list a {
  display:block; font-size:13px; color:var(--hc-text2);
  padding:7px 12px; border-radius:6px; transition:all 0.2s;
}
.cat-nav-list a:hover { background:var(--hc-bg2); color:var(--hc-text); text-decoration:none; }
.cat-nav-list a.current { background:var(--hc-accent); color:#fff; font-weight:600; }

/* FAQ section */
.faq-item {
  background:var(--hc-card); border:1px solid var(--hc-border);
  border-radius:var(--hc-radius); margin-bottom:12px; overflow:hidden;
}
.faq-q {
  padding:16px 20px; font-weight:600; cursor:pointer;
  display:flex; align-items:center; justify-content:space-between;
  font-size:15px; transition:background 0.2s;
}
.faq-q:hover { background:var(--hc-bg2); }
.faq-a { padding:0 20px 16px; font-size:14px; color:var(--hc-text2); display:none; line-height:1.7; }
.faq-item.open .faq-a { display:block; }
.faq-arrow { transition:transform 0.3s; font-size:12px; }
.faq-item.open .faq-arrow { transform:rotate(180deg); }

/* Footer */
.hc-footer {
  border-top:1px solid var(--hc-border); margin-top:60px;
  padding:30px 24px; text-align:center;
  font-size:13px; color:var(--hc-text3); line-height:1.8;
}
.hc-footer a { color:var(--hc-accent); }
.hc-footer-links { display:flex; justify-content:center; gap:24px; margin-bottom:14px; flex-wrap:wrap; }

/* Responsive */
@media(max-width:900px) {
  .hc-article { grid-template-columns:1fr; }
  .toc-box { display:none; }
  .hc-nav { display:none; }
  .hc-hero { padding:32px 24px; }
  .hc-cat-grid { grid-template-columns:repeat(auto-fill,minmax(200px,1fr)); }
}
@media(max-width:480px) {
  .hc-main { padding:16px; }
  .hc-hero .hc-stats { flex-wrap:wrap; gap:16px; }
}