:root{
  --fs:19px;
  --bg:#05080d; --bg2:#0a1018; --panel:#0e1621; --line:#1b2a3a;
  --text:#d9e2ec; --muted:#8a9bb0; --accent:#3cf2a0; --accent2:#5ab4ff; --warn:#ffb547;
  --card:#0c1a17; --card-line:#1f5c45;
  --serif:"Noto Serif SC","Source Han Serif SC","Songti SC","STSong","SimSun",serif;
  --sans:-apple-system,BlinkMacSystemFont,"PingFang SC","Hiragino Sans GB","Microsoft YaHei","Noto Sans SC",sans-serif;
  --mono:"JetBrains Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  --w:720px;
}
html[data-theme="light"]{
  --bg:#f6f3ec; --bg2:#ece7dc; --panel:#fffdf8; --line:#ddd5c4;
  --text:#2a2723; --muted:#77705f; --accent:#0d8a5a; --accent2:#1f6fb8; --warn:#b06a00;
  --card:#eef6f1; --card-line:#9fd0b6;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-snap-type:y proximity;-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--text);font-family:var(--serif);font-size:var(--fs);line-height:1.95;
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
.mono{font-family:var(--mono)}
a{color:var(--accent2)}
button{font:inherit;color:inherit}
.hide-sm{}
@media (max-width:600px){.hide-sm{display:none}}

/* progress + top bar */
.progress{position:fixed;inset:0 0 auto 0;height:3px;z-index:60;background:transparent}
.progress-bar{height:100%;width:0;background:linear-gradient(90deg,var(--accent),var(--accent2));box-shadow:0 0 10px var(--accent)}
.topbar{position:fixed;top:3px;left:0;right:0;z-index:50;display:flex;align-items:center;gap:8px;padding:6px 10px;
  font-family:var(--sans);font-size:14px;background:color-mix(in srgb,var(--bg) 78%,transparent);backdrop-filter:blur(10px);
  -webkit-backdrop-filter:blur(10px);border-bottom:1px solid var(--line);transition:transform .3s}
.topbar.hidden{transform:translateY(-120%)}
.tb-chapter{flex:1;text-align:center;color:var(--muted);white-space:nowrap;overflow:hidden;text-overflow:ellipsis;letter-spacing:.05em}
.tb-right{display:flex;gap:6px}
.tb-btn{background:transparent;border:1px solid var(--line);border-radius:8px;padding:5px 10px;cursor:pointer;color:var(--text);font-family:var(--sans);font-size:14px;line-height:1.2}
.tb-btn:hover,.tb-btn:focus-visible{border-color:var(--accent);color:var(--accent);outline:none}

/* TOC drawer */
.toc{position:fixed;top:0;bottom:0;left:0;width:min(360px,86vw);z-index:80;background:var(--panel);border-right:1px solid var(--line);
  transform:translateX(-102%);transition:transform .35s cubic-bezier(.2,.8,.2,1);overflow-y:auto;padding:16px 14px 24px;font-family:var(--sans)}
.toc.open{transform:none;box-shadow:0 0 60px rgba(0,0,0,.5)}
.toc-head{display:flex;justify-content:space-between;align-items:center;color:var(--accent);letter-spacing:.2em;font-size:13px;margin-bottom:10px}
.toc ol{list-style:none;margin:0;padding:0}
.toc li a{display:flex;flex-direction:column;padding:10px 12px;border-radius:10px;text-decoration:none;color:var(--text);border:1px solid transparent;margin-bottom:4px}
.toc li a:hover{border-color:var(--line);background:var(--bg2)}
.toc li a.active{border-color:var(--accent);background:color-mix(in srgb,var(--accent) 10%,transparent)}
.toc-label{font-size:12px;color:var(--accent);letter-spacing:.1em}
.toc-title{font-size:15px;line-height:1.5}
.toc-tip{color:var(--muted);font-size:12px;margin-top:16px;line-height:1.7}
.toc-backdrop{position:fixed;inset:0;background:rgba(0,0,0,.45);z-index:70}

/* pager */
.pager{position:fixed;right:14px;bottom:calc(14px + env(safe-area-inset-bottom));z-index:50;display:flex;gap:8px}
.pg-btn{background:color-mix(in srgb,var(--panel) 88%,transparent);border:1px solid var(--line);border-radius:999px;padding:8px 14px;cursor:pointer;
  font-family:var(--sans);font-size:14px;backdrop-filter:blur(8px);-webkit-backdrop-filter:blur(8px);box-shadow:0 6px 20px rgba(0,0,0,.25)}
.pg-btn:hover,.pg-btn:focus-visible{border-color:var(--accent);color:var(--accent);outline:none}
.pg-btn:disabled{opacity:.35;cursor:default}
.toast{position:fixed;left:50%;bottom:70px;transform:translateX(-50%) translateY(20px);opacity:0;pointer-events:none;z-index:90;
  background:var(--panel);border:1px solid var(--accent);color:var(--text);padding:8px 16px;border-radius:999px;font-family:var(--sans);font-size:14px;transition:.3s}
.toast.show{opacity:1;transform:translateX(-50%)}

/* cover */
.cover{min-height:100vh;min-height:100svh;display:flex;flex-direction:column;align-items:center;justify-content:center;position:relative;scroll-snap-align:start;
  text-align:center;padding:80px 20px;overflow:hidden;
  background:radial-gradient(ellipse at 50% 30%,color-mix(in srgb,var(--accent) 14%,transparent),transparent 60%),
             radial-gradient(ellipse at 80% 90%,color-mix(in srgb,var(--accent2) 12%,transparent),transparent 55%),var(--bg)}
.cover::before,.chapter-cover .cc-grid{content:"";position:absolute;inset:0;pointer-events:none;opacity:.35;
  background-image:linear-gradient(var(--line) 1px,transparent 1px),linear-gradient(90deg,var(--line) 1px,transparent 1px);
  background-size:44px 44px;mask-image:radial-gradient(ellipse at center,#000 30%,transparent 75%);-webkit-mask-image:radial-gradient(ellipse at center,#000 30%,transparent 75%)}
.cover-inner{position:relative;max-width:var(--w)}
.cover-hash{font-size:11px;color:var(--muted);word-break:break-all;opacity:.7;margin-bottom:28px}
.cover-kicker{color:var(--accent);font-size:12px;letter-spacing:.3em;margin:0 0 10px}
.cover-title{font-size:clamp(56px,14vw,120px);font-weight:900;letter-spacing:.12em;margin:0;line-height:1.15;
  background:linear-gradient(180deg,var(--text) 30%,var(--accent));-webkit-background-clip:text;background-clip:text;color:transparent;
  text-shadow:0 0 40px color-mix(in srgb,var(--accent) 25%,transparent)}
.cover-sub{font-size:clamp(18px,4.4vw,26px);letter-spacing:.25em;margin:14px 0 8px}
.cover-meta{color:var(--muted);font-family:var(--sans);font-size:14px;margin:0 0 36px}
.btn-start,.btn-resume{display:inline-block;margin:6px;padding:10px 26px;border-radius:999px;border:1px solid var(--accent);color:var(--accent);
  text-decoration:none;font-family:var(--sans);font-size:15px;letter-spacing:.1em;transition:.2s}
.btn-start:hover{background:var(--accent);color:var(--bg)}
.btn-resume[hidden]{display:none}
.btn-resume{border-color:var(--line);color:var(--text)}
.scroll-hint{position:absolute;bottom:22px;left:0;right:0;text-align:center;color:var(--muted);font-family:var(--sans);font-size:13px;letter-spacing:.2em;animation:bob 2s ease-in-out infinite}
@keyframes bob{50%{transform:translateY(6px);opacity:.6}}

/* prose */
.front{padding:60px 0 40px;scroll-snap-align:start}
.prose{max-width:var(--w);margin:0 auto;padding:30px 22px 80px}
.prose p{margin:0 0 1.1em;text-align:justify;text-indent:2em}
.prose blockquote p,.prose aside p,.prose li p,.cast p{text-indent:0}
.prose strong{color:color-mix(in srgb,var(--text) 80%,var(--accent))}
.prose code{font-family:var(--mono);font-size:.82em;background:var(--bg2);border:1px solid var(--line);padding:1px 6px;border-radius:5px;color:var(--accent)}
.prose h2{font-size:1.3em;margin:2.2em 0 .8em;padding-left:12px;border-left:4px solid var(--accent);line-height:1.5}
.prose blockquote{margin:1.6em 0;padding:4px 20px;border-left:3px solid var(--accent2);color:var(--muted);background:color-mix(in srgb,var(--accent2) 5%,transparent);border-radius:0 10px 10px 0}
.disclaimer{font-size:.9em}
.cast-title{margin-top:2em}
.cast ul{list-style:none;padding:0;display:grid;gap:10px}
.cast li{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:12px 16px;font-size:.92em;line-height:1.75}
.cast li strong{color:var(--accent);font-size:1.08em;margin-right:4px}
.scene-break{text-align:center;color:var(--accent);letter-spacing:1em;margin:2.4em 0;opacity:.7;font-size:.8em}

/* chapter cover = full-screen "page" */
.chapter-cover{min-height:100vh;min-height:100svh;position:relative;display:flex;align-items:center;justify-content:center;text-align:center;
  scroll-snap-align:start;padding:80px 20px;overflow:hidden;border-top:1px solid var(--line);
  background:radial-gradient(ellipse at 50% 45%,color-mix(in srgb,var(--accent) 10%,transparent),transparent 60%),var(--bg)}
.cc-inner{position:relative}
.cc-num{color:var(--accent);letter-spacing:.35em;font-size:12px;margin:0 0 18px}
.cc-label{font-size:clamp(20px,4vw,26px);letter-spacing:.5em;color:var(--muted);margin:0 0 6px;padding-left:.5em}
.cc-title{font-size:clamp(38px,9vw,72px);font-weight:900;letter-spacing:.12em;margin:0;line-height:1.3}
.appendix .cc-title{font-size:clamp(26px,6vw,46px);letter-spacing:.05em;max-width:16em}
.cc-hash{color:var(--muted);font-size:11px;margin-top:28px;opacity:.6;word-break:break-all}
.chapter-cover.inview .cc-title{animation:rise .9s ease both}
@keyframes rise{from{opacity:0;transform:translateY(18px);filter:blur(4px)}to{opacity:1;transform:none;filter:none}}

/* knowledge card */
.knowledge-card{position:relative;margin:2.4em -6px;padding:22px 22px 8px;border:1px solid var(--card-line);border-radius:16px;
  background:linear-gradient(160deg,var(--card),color-mix(in srgb,var(--card) 70%,var(--bg)));font-family:var(--sans);font-size:.88em;line-height:1.85;
  box-shadow:0 0 0 1px color-mix(in srgb,var(--accent) 8%,transparent),0 18px 40px rgba(0,0,0,.25)}
.knowledge-card::before{content:"";position:absolute;left:0;top:18px;bottom:18px;width:3px;border-radius:3px;background:var(--accent);box-shadow:0 0 12px var(--accent)}
.kc-title{font-weight:700;font-size:1.12em;line-height:1.6;margin-bottom:12px;color:var(--text)}
.kc-badge{display:block;font-family:var(--mono);font-size:10px;letter-spacing:.3em;color:var(--accent);margin-bottom:6px}
.knowledge-card p{text-align:left}
.knowledge-card strong{color:var(--accent)}
.knowledge-card ul,.knowledge-card ol{padding-left:1.3em}

/* appendix checklist */
.appendix .prose ol{list-style:none;counter-reset:ck;padding:0}
.appendix .prose ol>li{counter-increment:ck;position:relative;background:var(--panel);border:1px solid var(--line);border-radius:12px;
  padding:14px 16px 14px 58px;margin:0 0 12px;font-family:var(--sans);font-size:.88em;line-height:1.8}
.appendix .prose ol>li::before{content:counter(ck,decimal-leading-zero);position:absolute;left:14px;top:14px;font-family:var(--mono);font-weight:600;
  color:var(--bg);background:var(--accent);border-radius:7px;font-size:12px;padding:2px 6px;line-height:1.6}
.appendix .prose ol>li strong{color:var(--accent);display:inline}
.appendix .prose blockquote:last-child{border-left-color:var(--warn);color:var(--text);font-size:1.05em;background:color-mix(in srgb,var(--warn) 8%,transparent)}

.colophon{text-align:center;padding:60px 20px 120px;color:var(--muted);font-family:var(--sans);font-size:14px;border-top:1px solid var(--line)}
.colophon .mono{color:var(--accent);letter-spacing:.3em}

@media (max-width:600px){
  :root{--fs:17px}
  .prose{padding:24px 18px 70px}
  .knowledge-card{margin:2em -4px;padding:18px 16px 4px}
  .appendix .prose ol>li{padding-left:50px}
}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{animation:none!important;transition:none!important}}