*,*::before,*::after{box-sizing:border-box}
body{margin:0;font-family:"PingFang SC","Microsoft YaHei",sans-serif;color:#1a1a1a;background:#fff;line-height:1.82}
img{display:block;max-width:100%;height:auto}
a{color:#b45309;text-decoration:none}
a:hover{text-decoration:underline}
.wrap{width:min(880px,calc(100% - 36px));margin:0 auto}

.top{position:sticky;top:0;z-index:80;background:#fff;border-bottom:1px solid #e8e8e8}
.top-in{display:flex;align-items:center;justify-content:space-between;min-height:64px}
.brand{display:flex;align-items:center;gap:10px;font-weight:800;font-size:16px;color:#111}
.brand img{width:40px;border-radius:10px}
.nav{display:flex;gap:14px;flex-wrap:wrap}
.nav a{color:#555;font-size:14px}
.ham{display:none;border:1px solid #ddd;background:#fff;border-radius:8px;padding:8px 12px;cursor:pointer}
.drawer{display:none;flex-direction:column;padding:12px 18px 16px;border-top:1px solid #eee;background:#fff}
.drawer.on{display:flex}
.drawer a{padding:10px 0;border-bottom:1px solid #f3f3f3;color:#444;font-size:14px}

.intro{padding:44px 0 28px;text-align:center}
.intro h1{font-size:clamp(26px,4.2vw,38px);line-height:1.28;margin:0 0 14px;color:#111;font-family:Georgia,"Times New Roman",serif}
.intro .lead{color:#555;font-size:16px;max-width:720px;margin:0 auto 20px}
.toc{display:flex;flex-wrap:wrap;justify-content:center;gap:8px;margin-top:8px}
.toc a{font-size:13px;padding:6px 12px;border:1px solid #e5e5e5;border-radius:20px;color:#444;background:#fafafa}
.toc a:hover{background:#fff7ed;border-color:#fdba74;color:#9a3412;text-decoration:none}

.ch-divider{margin:0;padding:28px 0;background:linear-gradient(90deg,#fafafa 0%,#fff 50%,#fafafa 100%);border-top:1px solid #ececec;border-bottom:1px solid #ececec;text-align:center}
.ch-divider .num{font-family:Consolas,"Courier New",monospace;font-size:13px;letter-spacing:.18em;color:#a3a3a3;text-transform:uppercase}
.ch-divider .label{font-family:Georgia,"Times New Roman",serif;font-size:clamp(22px,3.5vw,30px);font-weight:700;color:#171717;margin:6px 0 0}

.chapter{padding:40px 0 52px;border-left:4px solid #fbbf24;margin-left:12px;padding-left:28px}
.chapter h2{font-size:22px;margin:0 0 14px;color:#111;font-family:Georgia,"Times New Roman",serif}
.chapter h3{font-size:17px;margin:22px 0 10px;color:#222}
.chapter p,.chapter li{color:#444;font-size:15px;margin:0 0 14px}
.chapter ul,.chapter ol{padding-left:20px;margin:0 0 14px}
.chapter figure{margin:18px 0;border:1px solid #eee;border-radius:12px;overflow:hidden;background:#fafafa}
.chapter figcaption{padding:10px 14px;font-size:13px;color:#666;border-top:1px solid #eee}
.ch-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin:16px 0}
.ch-grid img{aspect-ratio:9/16;object-fit:cover;width:100%}
.note{padding:16px 18px;border-radius:10px;background:#fffbeb;border:1px solid #fde68a;color:#78350f;font-size:14px;margin:16px 0}
.warn{padding:16px 18px;border-radius:10px;background:#fef2f2;border:1px solid #fecaca;color:#991b1b;font-size:14px;margin:16px 0}

.faq{padding:36px 0 48px;border-top:1px solid #f0f0f0}
.faq h2{font-family:Georgia,"Times New Roman",serif;font-size:24px;margin:0 0 16px}
.faq details{border:1px solid #ececec;border-radius:10px;padding:14px 18px;margin-bottom:10px;background:#fafafa}
.faq summary{font-weight:600;cursor:pointer;color:#222}
.faq p{margin:10px 0 0;color:#555;font-size:14px}

.sub-hero{padding:36px 0 8px}
.sub-hero h1{font-family:Georgia,"Times New Roman",serif;font-size:28px;margin:0}
.prose{padding:20px 0 56px}
.prose h2{font-size:20px;margin:28px 0 12px;color:#222}
.prose p,.prose li{color:#444;font-size:15px}
.related{margin-top:32px;padding:18px 20px;border:1px solid #e8e8e8;border-radius:12px;background:#f9fafb}
.related h3{margin:0 0 10px;font-size:16px}
.related a{display:block;padding:5px 0;color:#b45309;font-size:14px}

.ftr{padding:36px 0;background:#fafafa;border-top:1px solid #eee;font-size:13px;color:#888}
.ftr a{color:#666;margin-right:14px}
.err{min-height:58vh;display:grid;place-items:center;text-align:center;padding:40px 16px}
.err h1{font-size:48px;margin:0 0 12px;color:#ccc}

@media(max-width:720px){
  .chapter{margin-left:0;padding-left:18px;border-left-width:3px}
  .ch-grid{grid-template-columns:1fr}
  .ham{display:inline-flex}
  .nav{display:none}
}