:root{
  --bg:#efece3; --paper:#fffdf9; --ink:#221f1a; --ink-soft:#544f46; --ink-faint:#8a8275;
  --accent:#1d6b66; --accent-d:#13524e; --accent2:#a8521d;
  --line:#e2dccd; --line-soft:#efe9dc;
  --concept:#e9f3f1; --concept-b:#1d6b66;
  --summary:#f6f0e2; --summary-b:#c79a3c;
  --quiz:#efeaf4; --quiz-b:#6b4d8f;
  --note:#fbf1e4; --note-b:#c0732e;
  --warn:#f9eaea; --warn-b:#b34a3f;
  --sidebar:#2a2620; --sidebar-ink:#d9d2c4; --sidebar-dim:#9a9183; --sidebar-active:#7fd8d0;
  --maxw:51rem;
  --serif:"Noto Serif CJK SC","Source Han Serif SC","Songti SC",Georgia,"Times New Roman",serif;
  --sans:"PingFang SC","Microsoft YaHei","Noto Sans CJK SC","Hiragino Sans GB",-apple-system,system-ui,sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--serif);
  font-size:18px;line-height:1.9;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;}
#progress{position:fixed;top:0;left:0;height:3px;background:linear-gradient(90deg,var(--accent),var(--accent2));width:0;z-index:200;transition:width .1s ease-out;}
#layout{display:flex;}
#sidebar{position:fixed;top:0;left:0;width:316px;height:100vh;background:var(--sidebar);
  color:var(--sidebar-ink);overflow-y:auto;padding:0 0 3rem;z-index:120;border-right:1px solid #000;}
#sidebar::-webkit-scrollbar{width:9px}
#sidebar::-webkit-scrollbar-thumb{background:#4a443a;border-radius:6px}
#sidebar .side-head{padding:1.4rem 1.4rem 1rem;border-bottom:1px solid #423c32;position:sticky;top:0;background:var(--sidebar);z-index:2;}
#sidebar .side-head .bk{font-family:var(--sans);font-weight:700;font-size:1.02rem;color:#fff;letter-spacing:.02em;line-height:1.45}
#sidebar .side-head .sub{font-family:var(--sans);font-size:.72rem;color:var(--sidebar-dim);margin-top:.35rem;letter-spacing:.06em}
#main{margin-left:316px;flex:1;min-width:0;}
.wrap{max-width:var(--maxw);margin:0 auto;padding:3.2rem 2.2rem 6rem;}
ul.toc{list-style:none;margin:0;padding:.6rem .6rem 0;font-family:var(--sans);}
ul.toc li{margin:0}
ul.toc a{color:var(--sidebar-ink);text-decoration:none;display:block;padding:.34rem .7rem;border-radius:7px;font-size:.83rem;line-height:1.4}
ul.toc a:hover{background:#39332b;color:#fff}
li.part{margin-top:1rem;}
li.part>a{color:var(--sidebar-active);font-weight:700;font-size:.74rem;letter-spacing:.12em;padding-top:.5rem;border-top:1px solid #423c32;border-radius:0;}
li.chap{position:relative}
li.chap>a{padding-left:1.5rem;font-weight:600;color:#e9e3d6}
li.chap .tw{position:absolute;left:.45rem;top:.46rem;cursor:pointer;color:var(--sidebar-dim);font-size:.7rem;transition:transform .15s;user-select:none;width:1rem;text-align:center}
li.chap.open .tw{transform:rotate(90deg)}
ul.subs{list-style:none;margin:0;padding:0;max-height:0;overflow:hidden;transition:max-height .25s ease;}
li.chap.open ul.subs{max-height:46rem}
li.sub>a{padding-left:2.2rem;font-size:.78rem;color:var(--sidebar-dim)}
li.sub>a:hover{color:#fff}
ul.toc a.active{background:var(--accent);color:#fff !important}
li.sub>a.active{background:var(--accent-d);color:#fff !important}
#cover{position:relative;isolation:isolate;overflow:hidden;max-width:var(--maxw);aspect-ratio:210/297;min-height:760px;margin:0 auto;color:#092f34;text-align:left;background:#f3ecdf;box-shadow:0 22px 60px rgba(31,27,20,.18)}
#cover .cover-art{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;object-position:center;z-index:-2;display:block}
#cover::before{content:"";position:absolute;inset:0;z-index:-1;background:linear-gradient(90deg,rgba(247,241,230,.82) 0%,rgba(247,241,230,.46) 43%,rgba(247,241,230,0) 65%)}
#cover::after{content:"";position:absolute;left:3.8rem;top:2.8rem;width:2.4rem;height:6px;background:#c9531a;pointer-events:none}
#cover .cover-inner{height:100%;min-height:760px;display:flex;flex-direction:column;padding:3.5rem 3.8rem 3rem;position:relative;z-index:1}
#cover .cover-top{display:flex;align-items:center;justify-content:space-between;font-family:var(--sans);font-size:.66rem;letter-spacing:.2em;text-transform:uppercase;color:#31555a}
#cover .cover-top .edition{letter-spacing:.1em;color:#a8461c;font-weight:700}
#cover .cover-main{margin-top:6.2rem;max-width:38rem}
#cover .kicker{font-family:var(--sans);letter-spacing:.2em;font-size:.7rem;color:#a8461c;font-weight:750;text-transform:uppercase;margin-bottom:1.15rem}
#cover h1.booktitle{font-family:var(--sans);margin:0;color:#092f34;font-weight:850;letter-spacing:-.025em;line-height:1.02}
#cover h1.booktitle .fde{display:block;font-size:5.3rem;letter-spacing:-.055em;color:#c9531a;line-height:.9;margin-bottom:.45rem}
#cover h1.booktitle .cn{display:block;font-size:3.2rem;letter-spacing:.02em}
#cover .title-rule{width:72px;height:5px;background:#c9531a;margin:1.8rem 0 1.45rem}
#cover .booksub{font-family:var(--sans);font-size:1.55rem;font-weight:700;line-height:1.45;color:#143e43;margin:0;max-width:32rem;letter-spacing:.015em}
#cover .engtitle{font-family:Georgia,"Times New Roman",serif;margin-top:2.05rem;padding-top:1.15rem;border-top:1px solid rgba(9,47,52,.34);max-width:33rem;color:#31555a;line-height:1.42}
#cover .engtitle strong{display:block;color:#092f34;font-size:1.12rem;font-weight:600;letter-spacing:.01em}
#cover .engtitle span{display:block;font-size:.89rem;margin-top:.28rem;color:#4d6b6e}
#cover .cover-bottom{margin-top:auto;display:grid;grid-template-columns:1fr auto;gap:2rem;align-items:end;font-family:var(--sans);color:#31555a}
#cover .credit{font-size:.82rem;line-height:1.7;letter-spacing:.03em;background:rgba(247,241,230,.88);border-left:4px solid #c9531a;padding:.8rem 1rem;max-width:21rem;color:#31555a}
#cover .credit strong{display:block;font-size:1.02rem;color:#092f34;letter-spacing:.06em;margin-bottom:.1rem}
#cover .credit span{display:block}
#cover .source{text-align:right;font-size:.66rem;line-height:1.65;letter-spacing:.06em;text-transform:uppercase;color:#5e7779;max-width:15rem}
#print-contents{max-width:var(--maxw);margin:2rem auto;background:var(--paper);padding:3.4rem 3.8rem 4rem;box-shadow:0 16px 42px rgba(31,27,20,.12);font-family:var(--sans)}
#print-contents .contents-kicker{font-size:.72rem;letter-spacing:.22em;color:var(--accent2);font-weight:800}
#print-contents h2{font-size:2.65rem;line-height:1.1;margin:.55rem 0 .7rem;color:var(--ink);letter-spacing:.05em}
#print-contents .contents-intro{font-family:var(--serif);font-size:.94rem;color:var(--ink-soft);margin:0 0 1.5rem;max-width:38rem}
#print-contents .contents-group{font-size:.72rem;letter-spacing:.16em;color:var(--accent2);font-weight:800;margin:1.25rem 0 .35rem;padding-top:.7rem;border-top:1px solid var(--line)}
#print-contents .contents-row{display:grid;grid-template-columns:minmax(0,1fr) 2.2rem;gap:1rem;align-items:end;padding:.42rem 0;border-bottom:1px dotted #c9c0ae;text-decoration:none;color:var(--ink)}
#print-contents .contents-row:hover{color:var(--accent)}
#print-contents .contents-title{font-size:.91rem;line-height:1.45}
#print-contents .contents-page{text-align:right;font-family:Georgia,"Times New Roman",serif;font-size:.86rem;color:var(--ink-faint)}
.wrap h1{font-family:var(--sans);font-size:1.05rem;font-weight:800;letter-spacing:.16em;color:var(--accent);
  margin:4.5rem 0 0;padding:1rem 0 .4rem;border-bottom:2px solid var(--accent);text-align:left}
.wrap h1 .pnum{display:block;font-size:.72rem;letter-spacing:.2em;color:var(--accent2);margin-bottom:.3rem}
.wrap h2{font-family:var(--sans);font-size:1.72rem;font-weight:800;line-height:1.3;color:var(--ink);
  margin:3.2rem 0 1.1rem;padding-top:1rem;letter-spacing:.005em}
.wrap h2 .cnum{display:block;font-family:var(--sans);font-size:.78rem;font-weight:700;letter-spacing:.2em;color:var(--accent);margin-bottom:.5rem}
.wrap h3{font-family:var(--sans);font-size:1.22rem;font-weight:700;color:var(--accent-d);margin:2.4rem 0 .8rem;}
.wrap h4{font-family:var(--sans);font-size:1.02rem;font-weight:700;color:var(--ink);margin:1.6rem 0 .5rem;}
.wrap p{margin:0 0 1.05rem;}
.wrap a{color:var(--accent);text-decoration:none;border-bottom:1px solid rgba(29,107,102,.35)}
.wrap a:hover{border-bottom-color:var(--accent)}
.wrap strong{font-weight:700;color:#000}
.wrap em{font-style:normal;background:linear-gradient(transparent 62%, #ffe9a8 62%);padding:0 .05em}
.wrap ul,.wrap ol{margin:0 0 1.15rem;padding-left:1.5rem}
.wrap li{margin:.3rem 0}
.wrap blockquote{margin:1.4rem 0;padding:.5rem 1.2rem;border-left:3px solid var(--accent2);
  color:var(--ink-soft);background:#fbf8f1;font-size:.97rem}
.event-credit{display:grid;grid-template-columns:180px minmax(0,1fr);gap:1.25rem;align-items:center;
  margin:1.35rem 0 1.55rem;padding:1.1rem 1.2rem;background:#111;color:#f5f3ed;border-radius:12px;
  border:1px solid #2b2b2b;break-inside:avoid;page-break-inside:avoid}
.event-credit .event-logo{display:block;border:0}
.event-credit img{display:block;width:180px;max-width:100%;height:auto}
.event-credit p{margin:0;color:#d9d7d0;font-family:var(--sans);font-size:.84rem;line-height:1.65}
.event-credit strong{display:block;color:#fff;margin-bottom:.22rem}
.event-credit p a{color:#fff;border-bottom-color:rgba(255,255,255,.5)}
hr{border:none;border-top:1px solid var(--line);margin:2.5rem 0}
/* code blocks (for CS / technical books) */
.wrap pre{background:#2a2620;color:#e9e3d6;border-radius:10px;padding:1rem 1.1rem;overflow-x:auto;font-size:.86rem;line-height:1.6;margin:1.4rem 0;border:1px solid #1c1916}
.wrap pre code{font-family:"SFMono-Regular",Menlo,Consolas,monospace;background:none;color:inherit;padding:0;border:none}
.wrap code{font-family:"SFMono-Regular",Menlo,Consolas,monospace;background:#efe9dc;color:#a8521d;padding:.08em .35em;border-radius:5px;font-size:.88em}
.en{font-family:Georgia,"Times New Roman",serif;font-style:italic;color:var(--accent-d);white-space:nowrap}
.term{border-bottom:1px dotted var(--accent2);cursor:help;position:relative}
.box{border-radius:12px;padding:1.1rem 1.3rem 1.15rem;margin:1.6rem 0;font-size:.96rem;line-height:1.8;border:1px solid var(--line);}
.box .box-t{font-family:var(--sans);font-weight:800;font-size:.82rem;letter-spacing:.08em;display:flex;align-items:center;gap:.5rem;margin-bottom:.6rem}
.box p:last-child,.box ul:last-child,.box ol:last-child{margin-bottom:0}
.box .ic{font-size:1.05rem}
.box.learn{background:var(--concept);border-color:#bfe0db}
.box.learn .box-t{color:var(--concept-b)}
.box.concept{background:#fff;border:1px solid var(--line);border-left:4px solid var(--concept-b)}
.box.concept .box-t{color:var(--concept-b)}
.box.summary{background:var(--summary);border-color:#e6d6a8}
.box.summary .box-t{color:#9a7321}
.box.quiz{background:var(--quiz);border-color:#d6c9e6}
.box.quiz .box-t{color:var(--quiz-b)}
.box.quiz ol{counter-reset:q;list-style:none;padding-left:0}
.box.quiz ol li{counter-increment:q;padding-left:2rem;position:relative;margin:.55rem 0}
.box.quiz ol li::before{content:counter(q);position:absolute;left:0;top:.05rem;width:1.4rem;height:1.4rem;background:var(--quiz-b);color:#fff;border-radius:50%;font-family:var(--sans);font-size:.78rem;font-weight:700;display:flex;align-items:center;justify-content:center}
.box.note{background:var(--note);border-color:#ebcfa8}
.box.note .box-t{color:var(--note-b)}
.box.warn{background:var(--warn);border-color:#e6c2bc}
.box.warn .box-t{color:var(--warn-b)}
.box.who{background:#f3f1ec;border-color:var(--line)}
.box.who .box-t{color:var(--ink-soft)}
.fig{margin:1.6rem 0;padding:1.2rem 1.3rem;background:#fff;border:1px solid var(--line);border-radius:12px;text-align:center}
.fig .big{font-family:var(--sans);font-size:2.1rem;font-weight:800;color:var(--accent)}
.fig .cap{font-family:var(--sans);font-size:.82rem;color:var(--ink-faint);margin-top:.3rem}
figure.diagram{margin:1.9rem 0;padding:1.3rem 1.1rem .9rem;background:#fffdf9;border:1px solid var(--line);border-radius:14px;text-align:center;break-inside:avoid}
figure.diagram .d-t{font-family:var(--sans);font-weight:800;font-size:.92rem;color:var(--accent-d);margin-bottom:.9rem;letter-spacing:.01em}
figure.diagram svg{max-width:100%;height:auto;display:block;margin:0 auto}
figure.diagram figcaption{font-family:var(--sans);font-size:.82rem;color:var(--ink-soft);margin-top:.85rem;line-height:1.65;text-align:center;max-width:40rem;margin-left:auto;margin-right:auto}
figure.diagram text{font-family:var(--sans)}
@media(max-width:640px){figure.diagram{padding:.9rem .5rem .7rem}}
.wrap table{border-collapse:collapse;width:100%;margin:1.5rem 0;font-size:.9rem;font-family:var(--sans)}
.wrap th,.wrap td{border:1px solid var(--line);padding:.55rem .7rem;text-align:left;vertical-align:top}
.wrap th{background:#efe9dc;font-weight:700;color:var(--ink)}
.wrap tr:nth-child(even) td{background:#fbf8f1}
dl.gloss{margin:1rem 0}
dl.gloss dt{font-family:var(--sans);font-weight:700;color:var(--accent-d);margin-top:1rem}
dl.gloss dd{margin:.2rem 0 0;color:var(--ink-soft);font-size:.95rem}
.bookfoot{font-family:var(--sans);font-size:.8rem;color:var(--ink-faint);text-align:center;border-top:1px solid var(--line);margin-top:4rem;padding:2rem;line-height:1.8}
#menu-btn{display:none;position:fixed;top:.7rem;left:.7rem;z-index:140;background:var(--sidebar);color:#fff;border:none;border-radius:9px;width:44px;height:44px;font-size:1.3rem;cursor:pointer;box-shadow:0 2px 10px rgba(0,0,0,.25)}
#overlay{display:none;position:fixed;inset:0;background:rgba(0,0,0,.45);z-index:110}
@media(max-width:900px){
  #sidebar{transform:translateX(-100%);transition:transform .25s;width:84vw;max-width:340px}
  body.nav-open #sidebar{transform:translateX(0)}
  body.nav-open #overlay{display:block}
  #main{margin-left:0}
  #menu-btn{display:block}
  .wrap{padding:3.6rem 1.25rem 5rem}
  #cover{min-height:100svh;aspect-ratio:auto}
  #cover .cover-inner{min-height:100svh;padding:4.3rem 2rem 2.3rem}
  #cover .cover-main{margin-top:4.5rem}
  #cover h1.booktitle .fde{font-size:4rem}
  #cover h1.booktitle .cn{font-size:2.45rem}
  #cover .booksub{font-size:1.2rem}
  #cover .cover-bottom{grid-template-columns:1fr;gap:.8rem}
  #cover .source{text-align:left}
  .event-credit{grid-template-columns:1fr}
  body{font-size:17px}
}
@page{size:A4;margin:17mm 15mm}
@page:first{size:A4;margin:0}
@media print{
  html,body{background:#fff}
  body{font-size:11.5pt;line-height:1.62}
  #sidebar,#menu-btn,#overlay,#progress{display:none !important}
  #layout{display:block}
  #main{margin-left:0}
  .wrap{max-width:none;margin:0;padding:0}
  #cover{width:210mm;height:297mm;min-height:297mm;max-width:none;aspect-ratio:auto;margin:0;box-shadow:none;page-break-after:always;break-after:page}
  #cover::after{inset:10mm}
  #cover .cover-inner{height:297mm;min-height:297mm;padding:18mm 20mm 17mm}
  #cover .cover-main{margin-top:39mm;max-width:150mm}
  #cover h1.booktitle .fde{font-size:50pt}
  #cover h1.booktitle .cn{font-size:31pt}
  #cover .booksub{font-size:16pt;max-width:130mm}
  #cover .engtitle{margin-top:10mm;padding-top:5mm;max-width:126mm}
  #cover .engtitle strong{font-size:11.5pt}
  #cover .engtitle span{font-size:8.7pt}
  #cover .cover-bottom{grid-template-columns:1fr;gap:4mm;width:76mm;background:none;padding:0;border:0}
  #cover .source{text-align:left;padding-left:5mm}
  #print-contents{max-width:none;min-height:250mm;margin:0;padding:5mm 3mm 3mm;box-shadow:none;page-break-after:always;break-after:page}
  #print-contents .contents-kicker{font-size:8pt}
  #print-contents h2{font-size:28pt;margin:2mm 0 3mm}
  #print-contents .contents-intro{font-size:10pt;line-height:1.55;margin-bottom:5mm}
  #print-contents .contents-group{font-size:7.5pt;margin:4mm 0 1mm;padding-top:2.5mm}
  #print-contents .contents-row{grid-template-columns:minmax(0,1fr) 9mm;gap:4mm;padding:1.7mm 0;break-inside:avoid}
  #print-contents .contents-title{font-size:9.2pt;line-height:1.35}
  #print-contents .contents-page{font-size:9pt}
  .wrap h1{page-break-before:always;break-before:page}
  .wrap h2{page-break-before:always;break-before:page;break-after:avoid}
  .wrap h2,.wrap h3,.wrap h4{page-break-after:avoid;break-after:avoid}
  .box,figure.diagram,.fig,table,blockquote,pre{page-break-inside:avoid;break-inside:avoid}
  .event-credit{grid-template-columns:42mm minmax(0,1fr);gap:5mm;margin:4mm 0 5mm;padding:4mm;border-radius:2mm}
  .event-credit img{width:42mm}
  .event-credit p{font-size:8.5pt;line-height:1.55}
  dl.gloss dt{page-break-after:avoid;break-after:avoid}
  dl.gloss dd{page-break-before:avoid;break-before:avoid}
  dl.gloss{margin-top:2mm}
  dl.gloss dt{font-size:9.7pt;line-height:1.35;margin-top:2.6mm}
  dl.gloss dd{font-size:9.25pt;line-height:1.48;margin-top:.6mm}
  p,li{orphans:2;widows:2}
  .bookfoot{page-break-before:always;break-before:page;margin-top:2rem}
  .wrap a{color:var(--accent-d);border:none}
  .box .box-t .ic{display:none}
}