:root{
  --night:#082f45;
  --deep:#0b3c55;
  --ocean:#0f6f86;
  --teal:#2b9ca2;
  --gold:#d8ad55;
  --paper:#f7f2e8;
  --paper-2:#fffdf8;
  --ink:#243641;
  --muted:#637681;
  --line:#d8e4e5;
  --shadow:0 18px 48px rgba(7,47,67,.16);
  --page-width:900px;
}
*{box-sizing:border-box}
html{scroll-behavior:auto;background:var(--paper)}
body{margin:0;color:var(--ink);background:
  radial-gradient(circle at 10% 5%,rgba(91,192,209,.14),transparent 28rem),
  linear-gradient(180deg,#eaf8fb 0,#f7f2e8 32rem,#f7f2e8 100%);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei","Noto Sans CJK SC",sans-serif;
  line-height:1.75}
a{color:inherit}
button,input{font:inherit}
.skip-link{position:fixed;left:1rem;top:-5rem;z-index:99;padding:.65rem 1rem;background:#fff;border-radius:.65rem;box-shadow:var(--shadow)}
.skip-link:focus{top:1rem}
.site-header{background:linear-gradient(145deg,var(--night),var(--deep) 55%,#167c91);color:#fff;padding:0 5vw 3.5rem;position:relative;overflow:hidden}
.site-header::before,.site-header::after{content:"";position:absolute;border-radius:50%;filter:blur(1px);opacity:.28;pointer-events:none}
.site-header::before{width:26rem;height:26rem;background:#5fd4dd;right:-9rem;top:-13rem}
.site-header::after{width:18rem;height:18rem;background:#ffd785;left:-8rem;bottom:-12rem}
.brand-row{position:relative;z-index:2;max-width:1180px;margin:auto;display:flex;align-items:center;justify-content:space-between;gap:1rem;padding:1rem 0}
.brand,.top-links a{text-decoration:none}
.brand{display:flex;align-items:center;gap:.6rem;font-weight:750;letter-spacing:.03em}
.brand-mark{color:#ffd37c;font-size:1.4rem}
.top-links{display:flex;gap:1.15rem;font-size:.92rem;color:#d8f4f7}
.top-links a:hover{text-decoration:underline}
.hero{position:relative;z-index:2;max-width:1120px;margin:2rem auto 0;display:grid;grid-template-columns:minmax(0,1.1fr) minmax(250px,.62fr);gap:4rem;align-items:center}
.eyebrow{margin:0 0 .6rem;color:#bfeef2;font-weight:700;letter-spacing:.08em}
.hero h1{font-size:clamp(2.25rem,5vw,4.2rem);line-height:1.12;margin:.1rem 0 .3rem;letter-spacing:.02em}
.hero h2{font-size:clamp(1.5rem,3vw,2.3rem);line-height:1.3;margin:0;color:#ffe0a0}
.lead{font-size:clamp(1.05rem,1.8vw,1.28rem);max-width:42rem;color:#e9fbfc;margin:1.4rem 0}
.badges{display:flex;flex-wrap:wrap;gap:.65rem;margin:1.35rem 0}
.badges span{border:1px solid rgba(255,255,255,.33);background:rgba(255,255,255,.09);padding:.35rem .7rem;border-radius:999px;font-size:.88rem}
.edition-note{max-width:42rem;color:#cce9ec;font-size:.93rem}
.hero-cover{display:block;width:min(100%,310px);height:auto;margin:auto;border-radius:.35rem;box-shadow:0 24px 60px rgba(0,0,0,.34);background:#fff}
.reader-toolbar{position:sticky;top:0;z-index:30;display:flex;align-items:center;justify-content:center;gap:.55rem;padding:.65rem max(1rem,env(safe-area-inset-right));background:rgba(255,253,248,.94);backdrop-filter:blur(12px);border-bottom:1px solid var(--line);box-shadow:0 8px 22px rgba(8,47,69,.08)}
.tool-btn{border:1px solid #b9ced2;background:#fff;color:var(--deep);padding:.45rem .78rem;border-radius:.65rem;cursor:pointer;font-weight:700;white-space:nowrap}
.tool-btn:hover,.tool-btn:focus-visible{border-color:var(--ocean);box-shadow:0 0 0 3px rgba(15,111,134,.12);outline:none}
.tool-btn.secondary{color:#526a72;font-weight:600}
.page-control{display:flex;align-items:center;gap:.38rem;color:var(--muted);font-size:.92rem;white-space:nowrap}
.page-control input{width:4.2rem;border:1px solid #b9ced2;border-radius:.55rem;padding:.4rem .45rem;text-align:center;background:#fff;color:var(--ink)}
.progress-track{position:absolute;left:0;right:0;bottom:-1px;height:3px;background:transparent}
.progress-track span{display:block;width:0;height:100%;background:linear-gradient(90deg,var(--gold),var(--teal));transition:width .18s ease}
.layout{max-width:1320px;margin:0 auto;display:grid;grid-template-columns:260px minmax(0,1fr);gap:2rem;padding:2rem 1rem 4rem}
.toc-panel{position:sticky;top:5rem;align-self:start;max-height:calc(100vh - 6rem);overflow:auto;background:rgba(255,253,248,.92);border:1px solid var(--line);border-radius:1rem;padding:1rem;box-shadow:0 12px 30px rgba(8,47,69,.08)}
.toc-heading{display:flex;justify-content:space-between;align-items:center;margin-bottom:.75rem;color:var(--deep)}
.toc-close{display:none;border:0;background:transparent;font-size:1.8rem;line-height:1;cursor:pointer;color:var(--muted)}
.toc-panel nav{display:grid;gap:.25rem}
.toc-panel nav button{border:0;background:transparent;text-align:left;padding:.5rem .55rem;border-radius:.55rem;color:#405761;cursor:pointer;line-height:1.45}
.toc-panel nav button:hover,.toc-panel nav button.active{background:#e8f5f5;color:var(--deep);font-weight:700}
.toc-panel nav button.front{color:#6c7f87;font-size:.9rem}
.toc-footer{border-top:1px solid var(--line);margin-top:.8rem;padding-top:.8rem;display:grid;gap:.45rem;font-size:.88rem;color:var(--ocean)}
.toc-backdrop{display:none}
.toc-backdrop[hidden]{display:none!important}
.reader{min-width:0}
.reader-intro{max-width:var(--page-width);margin:0 auto 1.5rem;padding:1rem 1.2rem;background:#eef8f7;border-left:4px solid var(--teal);border-radius:.35rem .8rem .8rem .35rem}
.reader-intro h2{margin:0;color:var(--deep);font-size:1.1rem}
.reader-intro p{margin:.3rem 0 0;color:#526a72}
.pages{display:grid;gap:1.65rem;justify-items:center}
.page-shell{width:min(100%,var(--page-width));min-height:55vh;position:relative;scroll-margin-top:5rem}
.page-shell img{display:block;width:100%;height:auto;background:#fff;border:1px solid #e0e5e4;border-radius:.22rem;box-shadow:var(--shadow)}
.page-shell img.loading{min-height:70vh;background:linear-gradient(110deg,#f4f1e9 8%,#fff 18%,#f4f1e9 33%);background-size:200% 100%;animation:shimmer 1.45s linear infinite}
.page-label{display:block;text-align:center;color:#7b898d;font-size:.78rem;margin-top:.45rem}
@keyframes shimmer{to{background-position-x:-200%}}
.site-footer{text-align:center;background:#082f45;color:#d8eef1;padding:2.2rem 1rem 3rem}
.site-footer p{margin:.3rem 0}
.footer-links{display:flex;flex-wrap:wrap;justify-content:center;gap:1rem;margin-top:1rem}
.footer-links a{color:#ffe09c}
.back-top{position:fixed;right:1rem;bottom:1rem;z-index:35;width:2.8rem;height:2.8rem;border:0;border-radius:50%;background:var(--deep);color:#fff;box-shadow:var(--shadow);cursor:pointer;opacity:0;pointer-events:none;transform:translateY(.5rem);transition:.2s}
.back-top.show{opacity:1;pointer-events:auto;transform:none}
.noscript{text-align:center;padding:1rem;background:#fff5d7;margin:0}
@media(max-width:900px){
  .site-header{padding-left:1rem;padding-right:1rem}
  .hero{grid-template-columns:1fr;gap:2rem;text-align:center}
  .hero-copy{display:flex;flex-direction:column;align-items:center}
  .hero-cover{width:min(68vw,300px)}
  .layout{display:block;padding:1rem .55rem 3rem}
  .toc-panel{position:fixed;z-index:60;top:0;bottom:0;left:0;width:min(88vw,360px);max-height:none;border-radius:0 1rem 1rem 0;transform:translateX(-105%);transition:transform .22s ease;padding-top:max(1rem,env(safe-area-inset-top));}
  .toc-panel.open{transform:none}
  .toc-close{display:block}
  .toc-backdrop{position:fixed;inset:0;z-index:55;background:rgba(0,24,35,.48);display:block}
  .reader-intro{margin:.5rem .35rem 1rem}
  .pages{gap:1rem}
  .page-shell{scroll-margin-top:4.6rem}
}
@media(max-width:640px){
  .brand-row{align-items:flex-start}
  .brand{font-size:.9rem}
  .top-links{display:none}
  .site-header{padding-bottom:2.2rem}
  .hero{margin-top:1rem}
  .hero h1{font-size:2.25rem}
  .hero h2{font-size:1.45rem}
  .badges{justify-content:center}
  .reader-toolbar{justify-content:flex-start;overflow-x:auto;padding:.55rem .6rem;scrollbar-width:none}
  .reader-toolbar::-webkit-scrollbar{display:none}
  .tool-btn{padding:.42rem .66rem;font-size:.88rem}
  .tool-btn.secondary{display:none}
  .page-control input{width:3.6rem}
  .page-control span{font-size:.82rem}
  .layout{padding-left:.25rem;padding-right:.25rem}
  .page-shell img{border-left:0;border-right:0;border-radius:0;box-shadow:0 9px 22px rgba(8,47,69,.12)}
  .page-label{margin-top:.25rem}
}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.toc-panel,.back-top{transition:none}.page-shell img.loading{animation:none}}