@import url('https://fonts.googleapis.com/css2?family=Golos+Text:wght@400;500;600;700&family=Manrope:wght@400;500;600;700;800&display=swap');
:root{--green:#285b4b;--ink:#253c34;--muted:#859087;--line:#e4e9e2;--paper:#f6f7f2}*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font:14px 'Golos Text',sans-serif}button,select,input{font:inherit}button,a,select,input{ -webkit-tap-highlight-color:transparent}button{cursor:pointer;border:1px solid var(--line);background:white;color:var(--ink);border-radius:8px;padding:11px 17px;font-weight:500}button:hover{filter:brightness(.96)}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible{outline:3px solid #b6cba3;outline-offset:3px}button:disabled{opacity:.4;cursor:not-allowed}header{height:84px;display:flex;align-items:center;gap:22px;padding:0 40px;border-bottom:1px solid var(--line);background:#fff}.brand{color:var(--ink);text-decoration:none;display:flex;align-items:center;gap:13px;font-size:18px;letter-spacing:-.6px}.brand b{font-weight:400}.logo{width:40px;height:40px;background:var(--green);border-radius:12px;color:#fff;display:grid;place-content:center;font:bold 28px Georgia;position:relative}.logo span{font:14px sans-serif;position:absolute;right:5px;top:4px;color:#d0e2a7}.header-note{margin-left:auto;color:var(--muted);font-size:12px}.avatar{border-radius:50%;padding:11px;background:#edf0e8;font-size:11px;font-weight:600}.layout{display:grid;grid-template-columns:300px minmax(0,1fr);max-width:1680px;margin:auto}aside{padding:34px 26px;background:#fff;border-right:1px solid var(--line);min-height:calc(100vh - 84px)}.eyebrow{font-size:10px;letter-spacing:1.9px;font-weight:600;color:#7c927e}h2{font-family:Manrope,sans-serif;font-size:20px;letter-spacing:-.6px;margin:12px 0}p{line-height:1.6}.muted{color:var(--muted)}aside>p{font-size:12px;margin-bottom:28px}form>label{display:block;font-size:12px;margin:19px 0 0;font-weight:500}select{width:100%;margin-top:8px;border:1px solid var(--line);border-radius:7px;padding:11px 10px;background:#fff;color:var(--ink);font-size:13px}.scope{font-size:11px;color:#8a947e;line-height:1.5;margin:8px 0}fieldset{border:0;padding:0;margin:23px 0}legend{font-size:12px;margin-bottom:10px}.numbers{display:flex;gap:7px}.numbers label{flex:1;cursor:pointer}.numbers input{position:absolute;opacity:0}.numbers span{display:block;text-align:center;border:1px solid var(--line);border-radius:6px;padding:9px}.numbers input:checked+span{background:#eaf1e6;border-color:#9eb292;color:var(--green);font-weight:600}.numbers input:focus-visible+span{outline:2px solid var(--green)}.toggles{border-top:1px solid var(--line);padding-top:12px;margin-bottom:22px}.toggles label{display:flex;align-items:center;justify-content:space-between;font-size:12px;margin:16px 0}.toggles input{appearance:none;width:30px;height:18px;border-radius:10px;background:#cfd7cc;position:relative;cursor:pointer;margin:0}.toggles input:after{content:'';position:absolute;top:3px;left:3px;width:12px;height:12px;border-radius:50%;background:white;transition:left .15s}.toggles input:checked{background:var(--green)}.toggles input:checked:after{left:15px}.primary{background:var(--green);color:#fff;border-color:var(--green);width:100%;font-size:12px;padding:14px 8px}.aside-foot{display:flex;align-items:center;gap:14px;margin-top:40px;padding:19px 13px;background:#f7f8f2;border-radius:9px;color:#8a947d}.aside-foot>span{font-size:30px}.aside-foot p{font-size:11px;margin:0}main{padding:29px 40px 0;min-width:0}.breadcrumb{font-size:11px;color:#859087}.breadcrumb span{margin:0 9px;color:#bac3b6}.intro{display:flex;justify-content:space-between;align-items:center;padding:36px 0 33px;gap:15px}h1{font:700 clamp(25px,2.5vw,38px)/1.25 Manrope,sans-serif;letter-spacing:-1.7px;margin:12px 0}h1>span{color:#9aac74}.intro p{margin:0;color:#8a9389;font-size:13px}.formula-art{font:italic 40px Georgia;color:#54735a;transform:rotate(-8deg);background:#eaf0df;border-radius:50%;padding:14px 20px;width:180px;flex-shrink:0}.formula-art span{font-size:18px}.formula-art small{display:block;font:italic 16px Georgia;text-align:center;margin-top:8px}.sheetbar{background:#fff;border:1px solid var(--line);border-radius:10px;display:flex;justify-content:space-between;padding:15px 18px;align-items:center;gap:12px}.sheetbar>div:first-child{display:flex;gap:10px;align-items:center;flex-wrap:wrap}.sheetbar strong{font-size:12px}.sheetbar .muted{font-size:11px}.status-dot{width:6px;height:6px;border-radius:50%;background:#8aa36a}.actions{display:flex;gap:8px}.actions button{font-size:11px;white-space:nowrap}.dark{background:#eef2e9;border-color:#eef2e9}.tabs{display:flex;gap:30px;border-bottom:1px solid var(--line);margin-top:20px}.tabs button{border:none;background:none;border-radius:0;color:#8a948b;padding:18px 0 15px;font-size:13px}.tabs button[aria-selected=true]{color:var(--green);border-bottom:2px solid var(--green)}.tabs span{font-size:10px;background:#e6ecdf;border-radius:4px;margin-left:6px;padding:3px 6px}.work-heading{display:flex;justify-content:space-between;align-items:center;gap:15px;padding:23px 0}.work-heading h2{font-size:17px;margin:0 0 5px}.work-heading p{margin:0;color:#8a9389;font-size:11px}.pill{background:#edf0df;color:#829066;font-size:10px;padding:8px 10px;border-radius:5px;white-space:nowrap}.cards{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px}.card{border:1px solid var(--line);border-radius:11px;background:#fff;padding:21px;min-width:0}.card-head{display:flex;justify-content:space-between;align-items:center}.num{font-size:11px;color:#8c988a;background:#f3f5ee;padding:6px 9px;border-radius:5px}.difficulty{font-size:9px;letter-spacing:.4px;color:#8da071}.difficulty.hard{color:#b58b60}.equation{font-size:21px;margin:25px 0;text-align:center;overflow-x:auto;overflow-y:hidden;padding:4px 0}.tasktext{font-size:13px;line-height:1.7}.checkrow{display:flex;gap:8px;margin-top:18px}.checkrow input{width:100%;min-width:0;background:#fafbf7;border:1px solid var(--line);border-radius:6px;padding:10px 11px;font-size:12px}.checkrow button{font-size:11px;padding:9px 12px}.feedback{font-size:11px;min-height:15px;margin-top:7px;color:#a27148}.feedback.ok{color:var(--green)}.steps{font-size:12px;line-height:1.8}.steps .math{display:block;overflow:auto;padding:9px 0}.solution-answer{border-top:1px solid var(--line);margin-top:14px;padding-top:14px}.answer-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px}.answer-grid .equation{font-size:15px}.diagram{display:block;margin:10px auto;max-width:100%;height:160px}.notice{padding:12px;background:#fff5df;border-radius:8px;font-size:12px;margin-bottom:15px}footer{display:flex;justify-content:space-between;color:#a3ad9e;font-size:10px;padding:33px 0}dialog{max-width:440px;border:1px solid var(--line);border-radius:15px;padding:26px;color:var(--ink)}dialog::backdrop{background:#253c3455}dialog p{font-size:13px}dialog button{margin-top:12px}#printContent{display:none}@media(min-width:1500px){main{padding-left:60px;padding-right:60px}}@media(max-width:1100px){header{padding:0 24px}.layout{grid-template-columns:265px minmax(0,1fr)}aside{padding:30px 20px}main{padding:28px 24px 0}.formula-art{display:none}.sheetbar{align-items:flex-start;flex-direction:column}.work-heading{align-items:flex-start;flex-direction:column}.cards{gap:12px}.card{padding:16px}.checkrow{flex-wrap:wrap}.checkrow button{width:100%}.answer-grid{grid-template-columns:repeat(2,minmax(0,1fr))}}@media(max-width:700px){header{height:70px;padding:0 16px}.brand{font-size:14px}.header-note{display:none}.avatar{margin-left:auto}.layout{display:block}aside{min-height:0;border-right:0;padding:24px}form{display:grid;grid-template-columns:1fr 1fr;gap:0 15px}.scope,.toggles,.primary{grid-column:1/-1}.aside-foot{display:none}main{padding:25px 18px 0}.cards{grid-template-columns:1fr}.intro{padding:27px 0}h1{font-size:28px}.breadcrumb{font-size:10px}.checkrow{flex-wrap:nowrap}.checkrow button{width:auto}footer{gap:20px}fieldset{margin-bottom:10px}}
@page{size:A4;margin:17mm}@media print{body{background:#fff;color:#000;font:11pt serif}header,.layout,dialog{display:none!important}#printContent{display:block}.print-section+.print-section{break-before:page}.print-section h1{font:22pt serif;letter-spacing:0}.print-task{break-inside:avoid;padding:14px 0;border-bottom:1px solid #ddd}.print-task .equation{text-align:left;font-size:16px;margin:12px 0}.print-task .diagram{height:130px}.writing-space{height:40px}.steps{font:11pt/1.7 serif}.print-meta{font:10pt sans-serif;color:#555}.solution-answer{margin-bottom:10px}}
/* Touch controls and narrow screens; all assets use relative URLs. */
.steps > [data-tex],.solution-answer > [data-tex]{display:block;max-width:100%;overflow-x:auto;padding:8px 0}
select,.checkrow input{max-width:100%}.card-head{gap:8px}.feedback{overflow-wrap:anywhere}
@media screen and (max-width:900px){
 button,select,.checkrow input{min-height:44px}
 select,.checkrow input{font-size:16px}
 .numbers span{min-height:44px;display:grid;place-items:center}
 .toggles label{min-height:44px;margin:4px 0;cursor:pointer}
 .tabs button{min-height:48px;font-size:14px}
 .steps,.tasktext{font-size:14px}.feedback{font-size:13px;line-height:1.5}
 .steps .equation{font-size:17px}.toggles input{flex-shrink:0}
}
@media screen and (max-width:700px){
 form{grid-template-columns:minmax(0,1fr) minmax(0,1fr)}
 form>label{min-width:0}fieldset{grid-column:1/-1;min-width:0}
 .brand{min-width:0;letter-spacing:-.4px}.brand>span:last-child{max-width:210px;line-height:1.4}.logo{flex-shrink:0}
 .avatar{display:none}.tabs{gap:0;justify-content:space-between}
 .actions{width:100%}.actions button{flex:1;font-size:13px}
 .checkrow{flex-wrap:wrap}.checkrow input,.checkrow button{width:100%}
 .answer-grid{grid-template-columns:minmax(0,1fr)}
 .equation{font-size:19px}.card-head{flex-wrap:wrap}
 dialog{width:calc(100% - 32px);max-height:90dvh;overflow-y:auto}
 footer{flex-wrap:wrap}aside{padding:22px 18px}
}
@media screen and (min-width:701px) and (max-width:900px){.cards{grid-template-columns:minmax(0,1fr)}}