:root{color-scheme:light;--ink:#102d3d;--muted:#526572;--line:#dce5e9;--accent:#087c80;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;font-size:16px;background:#f4f7f9;color:var(--ink)}*{box-sizing:border-box}body{margin:0;line-height:1.65;overflow-wrap:anywhere}header{background:var(--ink);color:white;padding:22px max(20px,env(safe-area-inset-right)) 22px max(20px,env(safe-area-inset-left));display:flex;align-items:center;justify-content:space-between;gap:20px}.brand{display:flex;align-items:center;gap:12px;font-weight:650;font-size:1.125rem}.mark{display:grid;place-items:center;width:42px;height:42px;border:1px solid #90b9c9;border-radius:11px;font-size:.875rem;letter-spacing:.08em;color:#a7eeeb}.sub{display:block;color:#aec5d0;font-size:.875rem;font-weight:400}.edition{font-size:.75rem;letter-spacing:.15em;color:#b3c7d0}main{max-width:880px;margin:auto;padding:38px max(20px,env(safe-area-inset-right)) 20px max(20px,env(safe-area-inset-left))}.eyebrow{font-size:.75rem;letter-spacing:.12em;font-weight:650;color:var(--accent);margin:0 0 10px}h1{font-size:clamp(1.65rem,5.7vw,2.5rem);letter-spacing:-.035em;line-height:1.3;margin:0 0 13px}.intro{color:var(--muted);margin:0}.stats{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:22px 0;margin:28px 0 34px}.stats>div{padding:0 16px;border-right:1px solid var(--line)}.stats>div:first-child{padding-left:0}.stats>div:last-child{border:0}.stats strong{display:block;font-size:2rem;line-height:1.3;font-weight:650;font-variant-numeric:tabular-nums}.stats .status{font-size:1.125rem;line-height:2.3;color:var(--accent)}.stats span{font-size:.875rem;color:var(--muted)}.section-head{display:flex;justify-content:space-between;align-items:center;gap:16px;margin-bottom:14px}.section-head h2{font-size:1.125rem;margin:0}.section-head>span{font-size:.875rem;color:var(--muted)}.empty{background:white;border:1px solid var(--line);border-top:3px solid var(--accent);border-radius:4px 4px 16px 16px;padding:28px}.empty-label,.note-label{font-size:.875rem;color:var(--accent);font-weight:600}.empty h3{font-size:1.3rem;margin:12px 0 10px}.empty p{color:var(--muted);margin:0;max-width:36rem}.preview-format{display:flex;flex-wrap:wrap;gap:8px;margin-top:24px}.preview-format span{font-size:.875rem;padding:6px 11px;background:#edf5f5;border-radius:5px;color:#375c65}aside{margin-top:24px;padding:0 4px}aside p{margin:5px 0;color:var(--muted);font-size:.875rem}footer{text-align:center;font-size:.75rem;color:#637783;padding:30px 20px calc(25px + env(safe-area-inset-bottom))}details{background:white;border:1px solid var(--line);border-radius:12px;margin-bottom:14px}summary{cursor:pointer;min-height:48px;padding:18px;font-weight:600}summary:focus-visible{outline:3px solid var(--accent);outline-offset:3px}article{padding:20px;border-top:1px solid var(--line)}article h3{font-size:1.35rem;line-height:1.3;margin:0 0 8px}article p{margin:8px 0}article .example{color:var(--muted)}@media(max-width:420px){.edition{display:none}.empty{padding:23px}.stats>div{padding:0 10px}}@media(prefers-reduced-motion:no-preference){summary{transition:background .15s}summary:hover{background:#edf5f5}}@media(min-width:700px){header{padding-left:calc((100% - 840px)/2);padding-right:calc((100% - 840px)/2)}main{padding-top:48px}} 
button,select{font:inherit;min-height:46px;border:1px solid #b4cbce;border-radius:8px;padding:9px 14px;background:white;color:var(--ink);touch-action:manipulation;cursor:pointer}button:focus-visible,a:focus-visible,select:focus-visible,input:focus-visible{outline:3px solid #087c80;outline-offset:3px}.speech-controls{display:flex;align-items:center;flex-wrap:wrap;gap:10px;padding:16px;background:#e8f1f3;border-radius:12px;margin-bottom:28px}.speech-controls p{flex-basis:100%;font-size:.875rem;color:var(--muted);margin:0}.lesson-body{padding:0 22px 24px}.lesson-meta{color:var(--accent);font-weight:600}.hint,.adaptation{font-size:.875rem;color:var(--muted)}.adaptation{padding-left:12px;border-left:3px solid #b7d4d5}.lesson-nav{display:flex;flex-wrap:wrap;gap:8px;margin:18px 0}.lesson-nav a{display:flex;align-items:center;min-height:44px;padding:7px 12px;border:1px solid var(--line);border-radius:7px;text-decoration:none;color:var(--ink);font-size:.875rem}.part-title{font-size:1.15rem;margin:28px 0 12px;scroll-margin-top:18px}.lesson article{padding:20px 0}.english{font-size:1.125rem;line-height:1.8}.translation{color:var(--muted)}.listen{color:var(--accent);background:#eef7f7;margin:5px 0 8px;font-size:.875rem}.speaking{background:#087c80;color:white}.word-number{float:right;font-variant-numeric:tabular-nums;font-size:.875rem;color:var(--muted)}.phonetics{color:#53606b;font-family:"Segoe UI","Arial",sans-serif}.definition{font-style:italic}.collocations{background:#f4f7f9;padding:12px;border-radius:7px;font-size:.875rem}.dictionary{display:inline-flex;align-items:center;min-height:44px;color:var(--accent);font-size:.875rem}.quiz{padding:18px;background:#f1f6f7;border-radius:12px}.quiz fieldset{min-width:0;border:0;padding:0;margin:0}.quiz legend{font-size:1.1rem;font-weight:600;line-height:1.6}.option{display:flex;align-items:flex-start;gap:10px;padding:12px;border:1px solid #c8d7dc;background:white;border-radius:8px;margin:10px 0;cursor:pointer;min-height:48px}.option input{width:20px;height:20px;flex-shrink:0;margin-top:5px;accent-color:var(--accent)}.option-en,.option-zh{display:block}.option-zh{font-size:.875rem;color:var(--muted);margin-top:4px}.primary{background:var(--ink);color:white;margin-top:8px}.quiz-result:empty{display:none}.quiz-result{padding:14px;border-left:3px solid var(--accent);background:white}.incorrect{border-color:#9c651c}.sources{margin-top:25px}.sources h2{font-size:1.1rem}.sources a{color:var(--accent);min-height:44px;display:inline-flex;align-items:center}h1{font-size:clamp(1.65rem,5.7vw,2.2rem)}.heading{margin-bottom:10px}.stats{margin:22px 0}@media(max-width:420px){.lesson-body{padding:0 16px 18px}.quiz{padding:12px}main{padding-top:25px}.english{font-size:1.0625rem}}
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