:root{--navy:#122e42;--ink:#183043;--muted:#526676;--accent:#006f75;--line:#d8e2e8;--paper:#fff;--bg:#f3f6f8;--pale:#e9f3f4;--serif:"Times New Roman","SimSun","Songti SC",serif;--sans:"Times New Roman","SimHei","Heiti SC",sans-serif}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:105px}body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--serif);font-size:17px;line-height:1.8}a{color:var(--accent);text-underline-offset:4px}button,input{font:inherit}button{cursor:pointer}button,a,input,summary{outline-offset:4px}a:focus-visible,button:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid #008c95}h1,h2,h3,h4,nav,button,.eyebrow,.label,.brand{font-family:var(--sans)}h1,h2,h3{line-height:1.4;color:var(--navy)}h1{font-size:clamp(1.7rem,2.8vw,2.35rem);margin:6px 0 16px}h2{font-size:1.4rem;margin:34px 0 14px}h3{font-size:1.12rem;margin:20px 0 8px}p{margin:0 0 16px}ul,ol{padding-left:1.5em;margin:10px 0 18px}li{margin:6px 0}small{font-size:14px}.topbar{height:92px;background:var(--navy);color:white;display:flex;align-items:center;justify-content:space-between;padding:0 32px;gap:25px;position:sticky;top:0;z-index:20;box-shadow:0 1px 0 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a{display:block;text-decoration:none;font-size:15px;line-height:1.5;padding:8px 12px;margin:2px 0;color:#405969;border-left:3px solid transparent;border-radius:0 4px 4px 0}nav a:hover{background:#e1eaef}nav a.active{background:white;border-color:var(--accent);color:var(--accent);font-weight:bold}nav .nav-label{font-size:13px;letter-spacing:1px;color:#607885;margin:24px 12px 8px}nav .nav-label:first-child{margin-top:0}.sidebar-note{font-size:14px;color:#6b808c;margin:32px 15px;border-top:1px solid var(--line);padding-top:18px;line-height:1.9}main{max-width:1100px;width:100%;padding:35px clamp(24px,4vw,58px) 60px;min-height:calc(100vh - 160px)}.eyebrow{font-size:13px;color:var(--accent);letter-spacing:1px;font-weight:bold}.lead{color:#4d6473;font-size:18px;max-width:760px}.head-row{display:flex;justify-content:space-between;align-items:flex-start;gap:20px}.quiet-button{background:white;border:1px solid #c4d4dc;border-radius:4px;padding:6px 12px;white-space:nowrap;color:#3c5667;font-size:14px}.section-note{border-left:4px solid var(--accent);background:#e7f0f3;padding:18px 22px;margin:24px 0;color:#284957}.section-note p:last-child{margin:0}.paper{background:white;border:1px solid var(--line);padding:25px 28px;margin:20px 0;border-radius:5px}.paper>:first-child{margin-top:0}.paper>:last-child{margin-bottom:0}.lesson-tabs{display:flex;gap:18px;margin:25px 0;border-bottom:1px solid var(--line);flex-wrap:wrap}.lesson-tabs a{padding:8px 0;text-decoration:none;font-family:var(--sans);font-size:15px;color:var(--muted)}.lesson-tabs a:hover{color:var(--accent)}.two-col{display:grid;grid-template-columns:1fr 1fr;gap:20px}.two-col>.paper{margin:0}.step-list{counter-reset:steps;list-style:none;padding:0}.step-list>li{position:relative;border-bottom:1px solid var(--line);padding:15px 0 18px 48px;margin:0}.step-list>li:before{counter-increment:steps;content:counter(steps,decimal-leading-zero);position:absolute;left:0;top:13px;font-family:var(--sans);font-size:20px;color:var(--accent)}.step-list strong{display:block;font-family:var(--sans);font-size:18px;margin-bottom:3px}.step-list p{margin:0;color:#4c6270}.task-links{display:flex;gap:10px;flex-wrap:wrap;margin-top:18px}.task-links a{border:1px solid #b8cdd6;background:white;text-decoration:none;border-radius:4px;padding:7px 13px;font-size:15px}.task-links a:hover{background:var(--pale)}.format-table{width:100%;border-collapse:collapse;background:white;table-layout:fixed;font-size:16px}.format-table th{background:#e7eef2;text-align:left;font-family:var(--sans);font-weight:normal}.format-table th,.format-table td{padding:13px 16px;border-bottom:1px solid var(--line);vertical-align:top;overflow-wrap:anywhere}.format-table th:first-child,.format-table td:first-child{width:27%;color:#244b5d}.format-table td ul{margin:0}.format-table code{font-size:14px}.table-wrap{border:1px solid var(--line);border-radius:5px;overflow:hidden;margin:18px 0}.example{border:1px solid #c8d8df;background:#fff;padding:20px 24px;margin:16px 0}.example .label{font-size:14px;color:#486170;margin-bottom:8px;display:block}.example.good{border-left:4px solid var(--accent);background:#f4f9f9}.example.bad{border-left:4px solid #8b9eaa;background:#f5f7f8}.example p{margin:0;white-space:pre-line}.example .note{font-size:14px;color:#617887;margin-top:12px}.check-list{list-style:none;padding:0}.check-list li{border-bottom:1px solid #dde7eb;padding:12px 0;margin:0}.check-list label{display:flex;align-items:flex-start;gap:12px;cursor:pointer}.check-list input{width:19px;height:19px;flex:0 0 19px;margin-top:6px;accent-color:var(--accent)}.check-list input:checked+span{color:#628076;text-decoration:line-through}.check-list.static li{padding-left:26px;position:relative}.check-list.static 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var(--accent);text-decoration:none}.download-card b{display:block;font-family:var(--sans);font-size:20px;margin-bottom:8px}.download-card span{display:block;color:var(--muted);font-size:15px}.code-block{padding:18px 20px;background:#172e3c;color:#e4eef3;overflow:auto;white-space:pre-wrap;overflow-wrap:anywhere;font-size:15px;line-height:1.65;border-radius:4px}.minor{font-size:14px;color:var(--muted)}footer{position:relative;background:#e7eef2;color:#526a79;padding:20px 32px 20px 290px;font-size:14px;display:flex;flex-wrap:wrap;gap:12px 28px;border-top:1px solid var(--line)}.menu-button{display:none}.skip{position:absolute;top:-70px;left:15px;padding:10px 20px;background:white;z-index:100}.skip:focus{top:10px}.sr-only{position:absolute;clip:rect(0,0,0,0);width:1px;height:1px;overflow:hidden}#toast{position:fixed;bottom:24px;left:50%;transform:translateX(-50%);background:var(--navy);color:white;padding:8px 18px;display:none;border-radius:4px;font-size:15px;z-index:50}
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@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important}}@media print{.topbar,aside,footer,.lesson-tabs,.quiet-button,.next-lesson,.task-links,#toast,.progress-row button{display:none!important}.layout{display:block}body,main{background:white;color:black;max-width:none;font-size:11pt;padding:0}.paper,.example,.resource{break-inside:avoid;border:1px solid #bbb;box-shadow:none}.comparison{break-inside:auto}.comparison-content{display:block}.resource-grid,.two-col{display:block}a{color:black}h1{font-size:20pt}h2{font-size:15pt;break-after:avoid}h3{break-after:avoid}img{max-width:100%}.format-table{font-size:10pt}.download-grid{display:block}.download-card{display:block;margin:10px 0}.check-list input{appearance:none;border:1px solid black}main>article{max-width:none}}

/* Long references remain a continuous, copyable string. */
.reference-wrap-example{padding:18px 20px 18px calc(20px + 2em);border:1px solid var(--line);background:#fff;color:#000;text-indent:-2em;text-align:justify;line-height:1.8;overflow-wrap:normal}
.reference-wrap-example .reference-number{display:inline-block;width:2em;text-indent:0;white-space:nowrap}
.reference-wrap-example .reference-url{word-break:break-all;overflow-wrap:anywhere;hyphens:none}

.home-link{display:block;margin:24px 15px 0;font-size:14px}