/* Desktop-only chapter rail. Mobile navigation remains unchanged. */
@media (min-width:1180px){
  body{--desktop-rail-width:176px}
  body>main{margin-inline-start:var(--desktop-rail-width);width:calc(100% - var(--desktop-rail-width))}
  .desktop-chapter-rail{
    position:fixed;inset:0 auto 0 0;z-index:120;width:var(--desktop-rail-width);
    display:flex;flex-direction:column;padding:28px 18px 24px;
    color:#f5efe1;background:
      radial-gradient(circle at 12% 8%,rgba(80,139,119,.22),transparent 34%),
      linear-gradient(180deg,#082e29 0%,#0a3a33 55%,#062722 100%);
    box-shadow:inset -1px 0 rgba(231,214,176,.16),18px 0 46px rgba(0,24,20,.16)
  }
  .desktop-chapter-rail__brand{display:block;padding:3px 7px 24px;border-bottom:1px solid rgba(231,214,176,.18)}
  .desktop-chapter-rail__brand small{display:block;color:#d9aa62;font:700 9px/1.4 Arial,sans-serif;letter-spacing:.2em}
  .desktop-chapter-rail__brand strong{display:block;margin-top:8px;font:500 19px/1.25 Georgia,"Songti SC",serif}
  .desktop-chapter-rail nav{display:grid;gap:4px;margin-block:auto;padding-block:20px}
  .desktop-chapter-rail nav a{position:relative;display:grid;grid-template-columns:28px 1fr;align-items:center;gap:9px;min-height:53px;padding:7px 8px;border-radius:13px;color:rgba(241,239,227,.66);transition:color .2s ease,background-color .2s ease,transform .2s ease}
  .desktop-chapter-rail nav a:before{content:"";position:absolute;inset-inline-start:-18px;width:3px;height:0;border-radius:0 3px 3px 0;background:#e2b56d;transition:height .22s ease}
  .desktop-chapter-rail nav a b{color:#d9aa62;font:italic 500 15px/1 Georgia,serif;font-variant-numeric:tabular-nums}
  .desktop-chapter-rail nav a span{font:500 12px/1.3 "PingFang SC","Microsoft YaHei",sans-serif;white-space:nowrap}
  .desktop-chapter-rail nav a:hover{color:#fffaf0;background:rgba(255,255,255,.065);transform:translateX(2px)}
  .desktop-chapter-rail nav a.is-active{color:#fffaf0;background:linear-gradient(90deg,rgba(255,255,255,.11),rgba(255,255,255,.035))}
  .desktop-chapter-rail nav a.is-active:before{height:28px}
  .desktop-chapter-rail__foot{padding:18px 7px 2px;border-top:1px solid rgba(231,214,176,.18);color:rgba(224,234,228,.55);font:600 9px/1.6 Arial,sans-serif;letter-spacing:.14em}
  .desktop-chapter-rail__foot a{display:block;margin-top:5px;color:#eee2c8;font-size:10px;letter-spacing:.08em}
}
@media (max-width:1179px){.desktop-chapter-rail{display:none!important}}
@media (prefers-reduced-motion:reduce){.desktop-chapter-rail nav a,.desktop-chapter-rail nav a:before{transition:none!important}}