@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@400;500;600;700;800&display=swap');
:root{--ink:#233f37;--green:#175749;--paper:#f6f7f2;--muted:#67796f;--line:#dce4da;--lime:#dceda8}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:90px}body{margin:0;background:var(--paper);color:var(--ink);font-family:'Noto Sans SC',-apple-system,BlinkMacSystemFont,'Microsoft YaHei',sans-serif;font-size:16px;line-height:1.75}button,input,select{font:inherit}button,a,input,select{touch-action:manipulation}button{cursor:pointer;border:1px solid var(--line);background:#fff;color:var(--ink);border-radius:10px;padding:10px 17px;min-height:44px}button:hover{background:#edf3e5}a{color:inherit}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:3px solid #c7842b;outline-offset:3px}.top{position:sticky;top:0;z-index:10;display:flex;justify-content:space-between;align-items:center;padding:15px max(24px,calc((100vw - 1200px)/2));background:#f6f7f2f2;backdrop-filter:blur(12px);border-bottom:1px solid var(--line);gap:16px}.brand{display:flex;gap:12px;align-items:center;text-decoration:none;font-weight:700;font-size:20px;white-space:nowrap}.mark{display:grid;place-items:center;width:36px;height:36px;background:var(--green);color:#fff;border-radius:10px;font-size:26px}.edition{font-size:11px;font-weight:400;letter-spacing:2px;margin-left:15px;color:var(--muted)}nav{display:flex;align-items:center;gap:24px;font-size:14px}nav a{text-decoration:none}nav button{background:transparent}main{max-width:1200px;margin:auto;padding:0 28px}.hero{display:grid;grid-template-columns:1.3fr 1fr;gap:40px;padding:64px 0 46px;align-items:center}.eyebrow{font-size:11px;letter-spacing:2px;font-weight:600;color:var(--muted)}h1{font-size:clamp(34px,4.2vw,54px);line-height:1.32;letter-spacing:-2px;margin:20px 0}h1 span{color:var(--green)}.intro{color:var(--muted);font-size:17px;line-height:1.9}.badges{display:flex;flex-wrap:wrap;gap:8px;margin:24px 0}.badges span{font-size:12px;border:1px solid var(--line);padding:3px 10px;border-radius:30px}.primary{background:var(--green);color:white;border-color:var(--green);font-weight:600;padding:13px 23px}.primary:hover{background:#0f4035;color:#fff}.primary span{margin-left:30px}.micro{font-size:12px;color:var(--muted)}.hero-art{position:relative;padding:18px 8px 35px}.window{background:#e6ece0;border:1px solid #cbd6c6;border-radius:16px;padding:0 24px 24px;transform:rotate(-3deg);box-shadow:0 20px 45px #183e3010}.window-top{display:flex;align-items:center;gap:6px;padding:17px 0;border-bottom:1px solid #cbd6c6;font-size:11px;color:#687b67}.window-top i{width:8px;height:8px;border-radius:50%;background:#a5b69c}.window-top span{margin:auto}.folder{font-size:65px;line-height:1;margin-top:18px;color:#759c69}.window strong{font-size:14px}.paper{background:#fffdf6;border:1px solid #dedfd0;padding:18px;margin:20px 0 8px;border-radius:5px;transform:rotate(5deg)}.paper span{font-size:11px;color:#849080}.paper b{display:block;font-size:19px;margin:10px 0}.paper em{display:block;height:5px;border-radius:4px;background:#e7ebdc;width:85%;margin:10px 0}.paper em:last-child{width:60%}.art-note{font-size:11px;margin-top:20px;color:#5a7552}.floating{position:absolute;right:-3px;bottom:8px;background:var(--lime);padding:9px 16px;border-radius:8px;box-shadow:0 8px 20px #183e3010;transform:rotate(3deg);font-weight:700}.floating small{font-weight:400;font-size:11px;margin-left:10px}.progress-card{display:flex;justify-content:space-between;align-items:center;gap:25px;background:#fff;border:1px solid var(--line);border-radius:15px;padding:22px 28px}.progress-card h2{font-size:23px;margin:3px 0}.progress-card p{margin:0;color:var(--muted);font-size:13px}.bar-wrap{width:37%;display:flex;align-items:center;gap:18px;font-size:14px}progress{width:100%;height:8px;border:0;border-radius:8px;overflow:hidden;background:#e6eddf}progress::-webkit-progress-bar{background:#e6eddf}progress::-webkit-progress-value{background:var(--green)}progress::-moz-progress-bar{background:var(--green)}.storage-note{font-size:12px;color:var(--muted);margin:12px 3px 32px}.workspace{display:grid;grid-template-columns:290px minmax(0,1fr);gap:32px;align-items:start}aside{scroll-margin-top:90px}.catalog-heading{display:flex;justify-content:space-between;align-items:center}.catalog-heading h2{font-size:20px;margin:0}.catalog-heading span{font-size:11px;color:var(--muted)}.muted{font-size:13px;color:var(--muted);margin:5px 0 14px}.filter-label{display:flex;justify-content:space-between;align-items:center;font-size:12px;margin-bottom:16px}select{border:1px solid var(--line);border-radius:7px;padding:6px;background:white;color:var(--ink);max-width:100%}.group-title{font-size:11px;letter-spacing:1px;color:var(--muted);margin:22px 0 8px}.lesson-link{display:flex;align-items:center;gap:12px;width:100%;text-align:left;background:transparent;border:1px solid transparent;padding:11px 10px;border-radius:9px;margin:3px 0}.lesson-link.active{background:#e6eddd;border-color:#c6d5bb}.lesson-number{width:29px;height:29px;display:grid;place-items:center;flex-shrink:0;font-size:12px;background:#fff;border:1px solid var(--line);border-radius:50%}.lesson-link.completed .lesson-number{background:var(--green);color:#fff}.lesson-link strong{display:block;font-size:13px;font-weight:500}.lesson-link small{color:var(--muted);font-size:11px}.lesson-link.active strong{font-weight:700}article{padding:32px;background:#fff;border:1px solid var(--line);border-radius:16px;scroll-margin-top:90px;outline:none;min-width:0}.lesson-meta{display:flex;justify-content:space-between;color:var(--muted);font-size:12px;gap:15px}article h2{font-size:29px;line-height:1.4;margin:16px 0 10px;letter-spacing:-.7px}.goal{font-size:15px;color:var(--muted);margin-bottom:24px}.difference{border-left:3px solid #9eb889;background:#f1f5eb;padding:15px 18px;font-size:14px;border-radius:0 8px 8px 0}.difference b{display:block;font-size:12px;margin-bottom:5px;color:#536b48}.section-title{font-size:17px;margin:28px 0 8px}.step-hint{font-size:12px;color:var(--muted);margin:0 0 15px}.step{display:flex;gap:13px;padding:19px 0;border-bottom:1px solid #edf0e8;cursor:pointer}.step input,.check input{accent-color:var(--green);width:21px;height:21px;flex-shrink:0;margin-top:5px}.step strong{display:block;font-size:16px}.step p{margin:6px 0 0;color:#536259;font-size:15px;line-height:1.95}.step:has(input:checked){opacity:.65}.step:has(input:checked) strong{text-decoration:line-through;text-decoration-color:#839f78}.expected,.practice{padding:17px 20px;background:#f7f8f3;border-radius:10px;margin:22px 0;font-size:14px}.expected b,.practice b{display:block;margin-bottom:5px}.practice{background:#fff8e9}details{border:1px solid var(--line);border-radius:10px;margin:20px 0;padding:13px 17px;font-size:14px}summary{cursor:pointer;font-weight:600}details p{color:#536259}.check{display:flex;gap:10px;align-items:start;font-size:14px;padding:15px;background:#edf4e6;border-radius:10px}.lesson-actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:22px;align-items:center}.lesson-actions .primary{flex:1}.lesson-actions button:disabled{opacity:.45;cursor:not-allowed}.undo{font-size:12px;color:var(--muted);background:transparent;border:0}.completed-banner,.graduated{background:#e7f0d8;color:var(--green);border-radius:10px;padding:15px;margin-bottom:20px;font-weight:500}.tools{display:flex;justify-content:space-between;align-items:center;border-top:1px solid var(--line);padding:35px 0;margin-top:45px;gap:25px}.tools h2{font-size:17px;margin:0}.tools p{font-size:12px;color:var(--muted);max-width:500px}.tool-buttons{display:flex;gap:10px;flex-shrink:0}footer{border-top:1px solid var(--line);padding:24px 0 40px;color:var(--muted);font-size:11px}footer p{margin:4px 0}dialog{border:1px solid var(--line);border-radius:16px;color:var(--ink);width:min(560px,calc(100% - 30px));max-height:85vh;padding:24px}dialog::backdrop{background:#132d2766;backdrop-filter:blur(3px)}.dialog-heading{display:flex;align-items:center;justify-content:space-between}.dialog-heading h2{font-size:20px;margin:0}.dialog-heading button{font-size:24px;border:0;padding:0 10px}dialog p,dd{font-size:14px;color:var(--muted)}dt{font-size:14px;font-weight:600;margin-top:14px}dd{margin:3px 0 0;padding-bottom:10px;border-bottom:1px solid var(--line)}#toast{position:fixed;bottom:25px;left:50%;transform:translateX(-50%);background:var(--green);color:white;padding:10px 20px;border-radius:10px;z-index:30;font-size:14px;max-width:90%;display:none}.download{display:inline-block;padding:10px 14px;background:#edf3e5;border-radius:8px;margin:8px 8px 8px 0;font-size:14px}.file-demo{margin:10px 0;font-size:13px}.file-demo input{max-width:100%;font-size:13px}.file-demo output{display:block;overflow-wrap:anywhere}[hidden]{display:none!important}@media(max-width:900px){.edition{display:none}.workspace{grid-template-columns:240px minmax(0,1fr);gap:20px}article{padding:24px}.hero{gap:25px}h1{font-size:40px}.paper b{font-size:16px}}@media(max-width:680px){html{scroll-padding-top:78px}.top{padding:12px 16px;gap:8px}.brand{font-size:16px;gap:8px}.mark{width:29px;height:29px;font-size:22px}nav{gap:13px;font-size:12px}nav button{font-size:12px;padding:7px 11px}main{padding:0 18px}.hero{display:block;padding:32px 0 25px}.hero-art{display:none}h1{font-size:38px;margin:16px 0;letter-spacing:-1.5px}.intro{font-size:15px}.badges{margin:20px 0}.hero .primary{width:100%;display:flex;justify-content:space-between}.micro{text-align:center}.progress-card{display:block;padding:19px}.progress-card h2{font-size:21px}.bar-wrap{width:100%;margin-top:16px}.workspace{display:flex;flex-direction:column;gap:22px}aside{width:100%}#lesson-list{max-height:300px;overflow:auto;border:1px solid var(--line);border-radius:12px;padding:0 8px 8px;background:#f0f3eb}article{width:100%;padding:23px 18px}article h2{font-size:26px}.goal{font-size:14px}.step{gap:10px}.step p{font-size:15px}.lesson-actions 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