:root{--bg:#f6f5f0;--paper:#fffefa;--ink:#243932;--muted:#6c7871;--green:#1f544b;--green-soft:#e8eee6;--line:#e2e6dd;--orange:#d18b57;--amber:#fbf0dd;--shadow:0 12px 35px #263b3010;font-family:"Segoe UI","Microsoft YaHei",system-ui,sans-serif;color:var(--ink);background:var(--bg);font-synthesis:none}*{box-sizing:border-box}body{margin:0}a{color:inherit;text-decoration:none}button,input,textarea{font:inherit}button,a,input,textarea,summary{touch-action:manipulation}button{cursor:pointer}button:disabled{cursor:default;opacity:.5}button:focus-visible,a:focus-visible,input:focus-visible,textarea:focus-visible,summary:focus-visible{outline:3px solid #d9915c;outline-offset:4px}button{border:0}h1,h2,h3,p{margin-top:0}h1{letter-spacing:-1.5px}h2{font-size:24px;line-height:1.5}h3{font-size:17px;line-height:1.55}p{line-height:1.9}.topbar{height:92px;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;padding:0 4.5%;background:#fffefacc;gap:16px}.brand{display:flex;align-items:center;gap:12px;font-weight:700;font-size:21px;letter-spacing:1px}.brandmark{background:var(--green);color:#fff8e5;width:43px;height:43px;border-radius:13px;font-size:30px;text-align:center;position:relative;font-family:Georgia,serif;line-height:43px}.brandmark span{color:#f7bb81;font-size:22px;position:absolute;right:1px;top:-13px}.brand small{display:block;font-size:10px;font-weight:400;color:var(--muted);margin-top:3px;letter-spacing:2px}.top-actions{display:flex;align-items:center;gap:18px}.sync{font-size:12px;color:var(--muted);max-width:330px;white-space:normal}.sync:before{content:"";display:inline-block;width:6px;height:6px;background:#779583;border-radius:50%;margin-right:7px}.sync.problem{color:#965522}.sync.problem:before{background:#b7773d}.layout{display:grid;grid-template-columns:220px minmax(0,1fr);gap:45px;max-width:1440px;margin:auto;padding:40px 4.5% 50px;min-height:calc(100vh - 160px)}.sidebar{padding-top:12px}.nav-label{font-size:11px;color:#8c968d;letter-spacing:2px;margin:0 14px 22px}.nav-link{display:flex;align-items:center;gap:13px;padding:15px 16px;border-radius:10px;margin-bottom:5px;font-size:15px;color:#6c7871}.nav-link.active{background:var(--green-soft);color:var(--green);font-weight:650}.nav-link:hover{background:#ecede6}.sidebar-note{border-top:1px solid var(--line);margin:75px 14px 0;padding-top:24px}.sidebar-note p{font-size:13px;margin:12px 0 15px}.tiny{font-size:12px;color:var(--muted);line-height:1.8}.eyebrow{text-transform:uppercase;font-size:11px;font-weight:650;letter-spacing:1.8px;color:var(--muted)}main{min-width:0}main:focus{outline:none}.hero{background:#e9eee4;border:1px solid #e2e8db;border-radius:22px;padding:44px 38px;display:grid;grid-template-columns:1.25fr 1fr;align-items:center;gap:24px;position:relative;overflow:hidden}.hero h1{font-size:44px;line-height:1.4;margin:17px 0 17px;font-weight:650}.hero h1>span{color:#a16a43}.hero p{font-size:14px;color:#6b796e;line-height:1.9;margin-bottom:26px}.primary,.secondary,.quiet{display:inline-flex;align-items:center;justify-content:center;gap:14px;min-height:43px;border-radius:8px;padding:11px 18px;font-size:13px;font-weight:600;line-height:1.5}.primary{background:var(--green);color:#fffdf0;border:1px solid var(--green)}.primary:hover{background:#163e38}.secondary{background:var(--paper);color:var(--green);border:1px solid #ccd8cb}.quiet{background:transparent;color:var(--muted);border:1px solid var(--line)}.quiet:hover,.secondary:hover{background:#e9eee5}.hero .primary{font-size:12px;padding:13px 17px}.hero-visual{background:#fffefabb;min-height:207px;border:1px solid #f8fcf1;border-radius:15px;padding:32px 22px 0;transform:rotate(-3deg);box-shadow:13px 17px 0 #dfe6d9;font-family:Consolas,"Cascadia Code",monospace}.code-line{font-size:13px;margin-bottom:16px;white-space:nowrap;color:#7b8f80}.code-line>span{color:#b6bfb3;font-size:10px;margin-right:15px}.code-line b{font-weight:500;color:#344f40}.visual-note{border-top:1px dashed #d8dfd0;margin-top:23px;padding:14px 0;font:10px "Microsoft YaHei",sans-serif;color:#85927e;display:flex;justify-content:space-between}.visual-note i{font-size:22px;color:var(--orange);font-style:normal}.stats{display:grid;grid-template-columns:repeat(3,1fr);margin:27px 0 39px;border-bottom:1px solid var(--line);padding:0 0 26px}.stats>div{padding-left:30px;border-left:1px solid var(--line)}.stats>div:first-child{padding-left:5px;border:0}.stats strong{font-size:30px;display:block;font-weight:500;line-height:1.6;font-family:Georgia,serif}.stats small{font-size:17px;color:#9ca595;margin-left:4px}.stats span{font-size:12px;color:var(--muted)}.section-heading{display:flex;justify-content:space-between;align-items:center;gap:16px;margin-bottom:20px}.section-heading h2{font-size:21px;margin:6px 0 0}.text-link{font-size:12px;color:var(--green);font-weight:600;line-height:1.8}.text-link:hover{text-decoration:underline}.unit-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:17px}.unit-card{display:flex;flex-direction:column;background:var(--paper);border:1px solid var(--line);border-radius:14px;padding:22px 23px;transition:transform .15s,box-shadow .15s;min-width:0}.unit-card:hover{transform:translateY(-3px);box-shadow:var(--shadow);border-color:#bcccb7}.unit-number{display:flex;justify-content:space-between;font-family:Georgia,serif;font-size:26px;color:#a3b298;margin-bottom:15px}.unit-number>span{font-size:20px;color:#909c8c}.unit-card h3{margin-bottom:9px;font-weight:600}.unit-card>p{font-size:12px;color:var(--muted);margin-bottom:25px;flex:1}.card-bottom{display:flex;align-items:center;justify-content:space-between;gap:7px;flex-wrap:wrap}.card-bottom .tiny{font-size:10px}.badge{font-size:10px;background:#f0f0e9;color:#7c8577;padding:5px 8px;border-radius:5px;white-space:nowrap}.badge.green{background:#e4eddf;color:var(--green)}.note-card{background:#efeee7;border-radius:12px;padding:23px 25px;display:flex;gap:20px;align-items:center;margin-top:28px}.note-card h3{font-size:14px;margin-bottom:5px}.note-card p{font-size:12px;color:var(--muted);margin-bottom:0}.note-icon{font-size:30px;color:#9ba78d}.footer{max-width:1440px;padding:20px 4.5%;margin:auto;display:flex;justify-content:space-between;border-top:1px solid var(--line);color:#8c9687;font-size:11px;gap:15px}.page-title{font-size:31px;line-height:1.5;margin:13px 0 12px;font-weight:650}.muted{color:var(--muted);font-size:14px}.week-tabs,.lesson-tabs,.task-tabs{display:flex;gap:7px;flex-wrap:wrap;margin:27px 0}.week-tabs button,.lesson-tabs a,.task-tabs a{padding:11px 17px;border:1px solid var(--line);background:var(--paper);border-radius:8px;font-size:12px;color:var(--muted)}.week-tabs .selected,.lesson-tabs .selected,.task-tabs .selected{background:var(--green);border-color:var(--green);color:#fffdf4}.breadcrumb{display:flex;gap:10px;color:var(--muted);font-size:12px}.breadcrumb a{color:var(--green)}.lesson-card{background:var(--paper);border:1px solid var(--line);padding:32px;border-radius:16px;min-width:0}.step-top{display:flex;justify-content:space-between;align-items:center;margin-bottom:15px;gap:15px}progress{width:100%;height:5px;appearance:none;border:0;border-radius:5px;margin-bottom:27px;background:#edf0e8;overflow:hidden}progress::-webkit-progress-bar{background:#edf0e8}progress::-webkit-progress-value{background:#7c9d7a}progress::-moz-progress-bar{background:#7c9d7a}.teaching-text{font-size:18px;line-height:2.1;white-space:pre-line;min-height:145px;margin-bottom:30px}.gentle-note{font-size:12px;color:var(--muted);border-left:2px solid #d9c2a2;padding:6px 14px;background:#faf8ee}.step-controls{display:flex;justify-content:space-between;align-items:center;gap:15px;margin-top:32px;padding-top:22px;border-top:1px solid var(--line)}pre{background:#eef1e9;color:#29473d;border:1px solid #e0e6d9;border-radius:10px;padding:20px;overflow:auto;max-width:100%;font-size:13px;line-height:1.9;white-space:pre-wrap;overflow-wrap:anywhere}code{font-family:Consolas,"Cascadia Code",monospace}.explanation{font-size:14px;color:var(--muted);padding:8px 0 21px;line-height:1.9}.data-panel{margin:22px 0;border:1px solid var(--line);border-radius:11px;background:#fffefa;min-width:0;overflow:hidden}.data-panel>summary{padding:17px 20px;cursor:pointer;font-size:13px;font-weight:600}.data-panel>summary .muted{font-size:11px;margin-left:10px}.data-panel>section{padding:10px 20px 20px}.data-panel h3{margin-bottom:4px}.table-scroll{overflow:auto;border:1px solid var(--line);border-radius:8px;max-height:400px;max-width:100%}table{border-collapse:collapse;width:100%;white-space:nowrap;text-align:left;font-family:Consolas,"Microsoft YaHei",monospace;font-size:12px}th{background:#eaf0e4;font-weight:600;color:#486044;position:sticky;top:0}td,th{padding:12px 15px;border-bottom:1px solid var(--line)}tr:last-child td{border-bottom:0}tbody tr:nth-child(even){background:#fafbf6}.null{color:#9c8269;font-style:italic}.question{font-size:21px;line-height:1.8;font-weight:600;margin-bottom:24px}fieldset{padding:0;margin:0 0 24px;border:0;min-width:0}.option{display:flex;align-items:center;gap:14px;border:1px solid var(--line);padding:17px;border-radius:10px;margin-bottom:11px;font-size:14px;line-height:1.7;cursor:pointer}.option:hover{border-color:#a1b898;background:#f6f8f0}.option:has(input:checked){background:#e8efe2;border-color:#77966b}.option input{accent-color:var(--green);width:17px;height:17px;flex-shrink:0}.option-letter{font:12px Georgia,serif;color:#87917e}.feedback{padding:20px;border-radius:10px;margin-top:22px;font-size:14px;line-height:1.8}.feedback p{margin:7px 0 0}.feedback button{margin-top:16px}.feedback.success{background:#e9f1e3;border:1px solid #cdddc1;color:#365432}.feedback.warning{background:var(--amber);border:1px solid #e6cfab;color:#805b31}.mobile-practice-note{display:none;background:var(--amber);padding:15px;border-radius:9px;font-size:12px;color:#805b31}.editor-label{display:flex;justify-content:space-between;gap:10px;font-size:13px;font-weight:600;margin:24px 0 10px}.editor-label span{color:#8c9685;font-size:10px;font-weight:400}.sql-editor{width:100%;min-height:235px;resize:vertical;border:1px solid #cdd8c4;border-radius:10px;padding:20px;background:#f5f7ef;color:#294237;font:14px/1.9 Consolas,"Cascadia Code","Microsoft YaHei",monospace;tab-size:2}.editor-controls{display:flex;flex-wrap:wrap;gap:9px;margin:18px 0}.editor-controls .quiet{font-size:11px;padding:10px 12px}.hint-box{padding:18px 20px;background:#f8f1e2;border-radius:9px;margin-top:20px;color:#7b5c32;font-size:13px;line-height:1.8}.hint-box p{margin:8px 0}.reference{background:#f3f2ea;border-radius:9px;padding:18px;margin-top:20px;font-size:13px}.reference summary{cursor:pointer;font-weight:600;line-height:1.8}.reference p{margin-bottom:8px}.result-title{display:flex;align-items:center;justify-content:space-between;margin:25px 0 12px}.result-title h3{margin-bottom:0}.finish-stats{display:grid;grid-template-columns:repeat(3,1fr);padding:22px 0;margin:20px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line);gap:15px}.finish-stats strong,.finish-stats span{display:block}.finish-stats strong{font-size:22px;font-weight:500;margin-bottom:9px}.finish-stats span{font-size:11px;color:var(--muted)}.choice-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;margin:25px 0}.choice-grid button{display:flex;flex-direction:column;gap:11px;padding:20px 17px;background:#f3f5ed;border:1px solid #dde5d5;border-radius:10px;text-align:left;color:var(--ink)}.choice-grid button:hover{background:#e6eedf;border-color:#96b08c}.choice-grid button>span{font-size:24px;color:#7f9874}.choice-grid strong{font-size:14px}.choice-grid small{font-size:11px;line-height:1.8;color:var(--muted)}.review-list{display:grid;gap:13px;margin:27px 0}.review-item{display:flex;justify-content:space-between;align-items:center;gap:22px;background:var(--paper);border:1px solid var(--line);padding:23px;border-radius:12px}.review-item:hover{border-color:#9db492}.review-item h3{margin:8px 0 0;font-weight:600;font-size:16px}.review-item p{font-size:12px;color:var(--muted);margin:8px 0 0}.review-item>span{white-space:nowrap;font-size:12px;color:var(--green)}.summary-text{width:100%;height:380px;padding:17px;background:#f7f8f2;border:1px solid var(--line);border-radius:9px;font-size:13px;line-height:1.9;resize:vertical;margin-top:15px;color:var(--ink)}.toast{position:fixed;bottom:26px;left:50%;transform:translateX(-50%);background:#243e33;color:#fffefa;padding:16px 23px;box-shadow:var(--shadow);border-radius:10px;max-width:calc(100vw - 32px);font-size:13px;line-height:1.8;z-index:100}dialog{border:1px solid var(--line);border-radius:16px;padding:32px;max-width:560px;width:calc(100% - 30px);color:var(--ink);background:var(--paper);box-shadow:var(--shadow)}dialog::backdrop{background:#1c302866}.dialog-close{position:absolute;right:16px;top:10px;font-size:25px;background:transparent;color:var(--muted)}dialog p{font-size:14px;line-height:1.9}.login-page{min-height:100vh;display:grid;place-items:center;padding:25px;background:var(--green-soft)}.login-card{background:var(--paper);padding:46px;border:1px solid #dce4d5;border-radius:22px;max-width:500px;width:100%;box-shadow:var(--shadow)}.login-card h1{font-size:35px;line-height:1.5;margin:20px 0}.login-card label{font-size:13px;font-weight:600}.login-card input{width:100%;padding:14px;border:1px solid #cad5c2;border-radius:8px;margin:12px 0 17px;background:#f8faf3}.login-card button{width:100%}.login-card .tiny{margin-top:25px}.sr-only,.skip{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.skip:focus{position:fixed;top:8px;left:8px;width:auto;height:auto;padding:10px;background:white;clip:auto;z-index:1000}#example-result{margin-top:20px}
@media(min-width:1550px){.hero{padding:50px}.hero h1{font-size:50px}}
@media(max-width:1050px){.layout{grid-template-columns:180px minmax(0,1fr);gap:25px;padding:30px 3%}.topbar{padding:0 3%}.hero{padding:30px 25px;grid-template-columns:1fr 0.9fr}.hero h1{font-size:35px}.hero-visual{padding:25px 15px 0}.code-line{font-size:11px}.code-line>span{margin-right:9px}.sidebar-note{margin-left:10px;margin-right:0}.nav-link{padding-left:12px;font-size:13px}.lesson-card{padding:25px}.choice-grid{grid-template-columns:1fr}.choice-grid button{display:grid;grid-template-columns:30px 1fr;gap:7px 12px}.choice-grid small{grid-column:2}.choice-grid button>span{grid-row:1 / 3}.unit-card{padding:18px}.card-bottom .tiny{display:none}}
@media(max-width:760px){.topbar{height:auto;min-height:77px;padding:17px 20px;align-items:flex-start}.brand{font-size:18px;gap:10px}.brandmark{width:36px;height:36px;line-height:36px;font-size:25px;border-radius:10px}.brandmark span{font-size:19px;top:-11px}.brand small{font-size:9px}.top-actions{flex-direction:column;align-items:flex-end;gap:5px;max-width:48%}.sync{font-size:10px;max-width:180px}.top-actions .quiet{min-height:25px;font-size:10px;padding:3px 8px}.layout{display:block;padding:0 20px 30px;min-height:calc(100vh - 140px)}.sidebar{display:flex;overflow:auto;gap:8px;padding:15px 0 20px;margin-bottom:0;scrollbar-width:thin}.sidebar .nav-label,.sidebar-note{display:none}.nav-link{white-space:nowrap;padding:9px 11px;border-radius:7px;font-size:11px;gap:6px;margin:0;flex-shrink:0}.hero{display:block;padding:30px 24px;border-radius:16px}.hero h1{font-size:36px;letter-spacing:-1px;margin-top:15px}.hero p{font-size:12px}.hero-visual{display:none}.hero .primary{font-size:11px}.stats{margin:23px 0 28px;padding-bottom:21px}.stats>div{padding-left:15px}.stats strong{font-size:27px}.stats small{font-size:15px}.stats span{font-size:10px}.section-heading h2{font-size:18px}.section-heading .text-link{font-size:10px;white-space:nowrap}.eyebrow{font-size:10px;letter-spacing:1px}.unit-grid{grid-template-columns:1fr;gap:12px}.unit-card{padding:19px 21px}.unit-number{font-size:23px;margin-bottom:9px}.unit-card h3{font-size:17px}.unit-card>p{margin-bottom:18px}.card-bottom .tiny{display:block;font-size:10px}.note-card{padding:18px;gap:13px}.note-card h3{font-size:13px}.note-card p{font-size:11px}.note-icon{font-size:24px}.footer{font-size:10px;padding:18px 20px;display:block;line-height:1.8}.footer span{display:block}.page-title{font-size:27px;margin-top:10px}.muted{font-size:13px}.week-tabs,.lesson-tabs,.task-tabs{gap:6px;margin:22px 0}.week-tabs button,.lesson-tabs a,.task-tabs a{font-size:11px;padding:10px 12px}.lesson-tabs{display:grid;grid-template-columns:repeat(4,1fr);gap:5px}.lesson-tabs a{text-align:center;padding:11px 5px;font-size:10px}.lesson-card{padding:23px 20px;border-radius:12px}.lesson-card h2{font-size:21px}.teaching-text{font-size:16px;line-height:2.05;min-height:0}.step-controls{gap:10px;margin-top:25px;padding-top:20px}.step-controls .primary,.step-controls .quiet{padding:10px 11px;font-size:11px}.step-controls .tiny{font-size:10px}.question{font-size:18px!important;line-height:1.9}.option{padding:14px 12px;gap:10px;font-size:13px}.option input{width:16px;height:16px}.feedback{padding:16px;font-size:13px}.feedback .tiny{font-size:11px}.data-panel>summary{font-size:12px;padding:15px}.data-panel>summary .muted{display:block;font-size:10px;margin:6px 0 0 15px}.data-panel>section{padding:7px 12px 15px}td,th{padding:10px 12px;font-size:11px}.mobile-practice-note{display:block}.sql-editor{font-size:16px;min-height:230px;padding:15px}.editor-label span{display:none}.editor-controls .primary{font-size:12px}.editor-controls .quiet{font-size:10px}.finish-stats{gap:10px}.finish-stats strong{font-size:18px}.finish-stats span{font-size:10px}.review-item{padding:18px;gap:14px}.review-item>span{font-size:10px}.review-item h3{font-size:14px}.breadcrumb{font-size:10px}.summary-text{font-size:12px}.login-card{padding:30px}.login-card h1{font-size:30px}pre{padding:15px;font-size:12px}dialog{padding:27px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}