:root{--bg:#f5f6f2;--paper:#fff;--ink:#1d302c;--muted:#66746e;--line:#e0e5dd;--green:#164e43;--green2:#28715b;--mint:#eaf1e7;--lime:#d9edb1;--amber:#b8782f;--red:#ac493e;--radius:16px;--shadow:0 10px 35px #193d2b08}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;font-size:15px;line-height:1.6}button,input,select,textarea{font:inherit}button,a,input,select,textarea{touch-action:manipulation}button,a{ -webkit-tap-highlight-color:transparent}button{cursor:pointer}a{color:inherit;text-decoration:none}button{color:inherit}button:disabled{cursor:default;opacity:.55}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,textarea:focus-visible,summary:focus-visible{outline:3px solid #64a588;outline-offset:3px}h1,h2,h3,p{margin:0}h1,h2{letter-spacing:-.04em;line-height:1.16}h1{font-family:Georgia,"Times New Roman",serif;font-weight:400;font-size:46px}h2{font-family:Georgia,serif;font-size:29px;font-weight:400}h3{font-size:17px;line-height:1.35;letter-spacing:-.02em}small{font-size:12px}svg{display:block}.muted{color:var(--muted)}.eyebrow{font-size:10px;letter-spacing:.16em;text-transform:uppercase;font-weight:750;color:var(--green2)}.skip{position:fixed;left:12px;top:-100px;z-index:500;padding:12px;background:#fff}.skip:focus{top:12px}.sidebar{width:246px;position:fixed;inset:0 auto 0 0;padding:29px 20px 18px;background:#fcfcf9;border-right:1px solid var(--line);display:flex;flex-direction:column;z-index:30;overflow-y:auto}.brand{display:flex;gap:11px;align-items:center;margin:0 7px 34px}.brand img{width:39px;height:39px}.brand b{display:block;font-size:17px;line-height:1.2;letter-spacing:-.5px}.brand span{display:block;font-size:10px;letter-spacing:.16em;color:var(--muted);margin-top:5px}.nav-main{display:grid;gap:5px}.nav-link{display:flex;align-items:center;gap:11px;font-size:13px;padding:10px 13px;border-radius:8px;min-height:42px;color:#52615c}.nav-link:hover{background:#eff2eb}.nav-link.active{background:var(--green);color:#fff;font-weight:600}.nav-icon{width:18px;text-align:center;font-size:16px}.nav-heading{font-size:10px;letter-spacing:.14em;color:#8b958e;font-weight:700;margin:25px 13px 9px}.section-nav .nav-link{font-size:12px;gap:10px;padding:7px 10px;min-height:36px}.section-nav .nav-link.active{background:#e7eee3;color:var(--green)}.nav-num{width:29px;flex-shrink:0;color:#829088;font-size:11px;font-variant-numeric:tabular-nums}.section-nav .active .nav-num{color:var(--green)}.nav-dot{margin-left:auto;width:5px;height:5px;background:#90ad66;border-radius:50%}.sidebar-bottom{margin-top:auto;padding:24px 9px 0}.save-status{font-size:11px;color:var(--muted);display:flex;gap:8px;align-items:center}.save-dot{width:6px;height:6px;border-radius:50%;background:#87a663}.workspace{margin-left:246px;transition:margin-right .18s}.topbar{height:72px;padding:0 44px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line);background:#fcfcf9}.breadcrumbs{font-size:12px;color:#79857e;display:flex;align-items:center;gap:12px}.breadcrumbs strong{font-weight:500;color:#354a40}.top-actions{display:flex;align-items:center;gap:16px}.top-badge{font-size:11px;background:#eaf0e3;padding:5px 10px;border-radius:30px;color:#527044}.avatar{width:32px;height:32px;border-radius:50%;background:#e7eadf;display:grid;place-items:center;font-size:12px;font-weight:700}.icon-btn{border:1px solid var(--line);background:#fff;border-radius:8px;min-width:34px;min-height:34px;display:grid;place-items:center}.text-btn{border:0;background:none;color:var(--green);font-size:12px;font-weight:650;padding:5px 0}.btn{border:1px solid var(--line);background:#fff;padding:10px 17px;border-radius:9px;font-size:12px;font-weight:650;display:inline-flex;align-items:center;justify-content:center;gap:10px;min-height:41px}.btn:hover{background:#f2f5ec;border-color:#bdcbb9}.btn.primary{background:var(--green);color:#fff;border-color:var(--green)}.btn.primary:hover{background:#246652}.btn.light{background:var(--lime);color:#233c29;border-color:var(--lime)}.btn.small{padding:7px 11px;font-size:11px;min-height:33px}.btn.danger{color:var(--red)}.btn svg{width:15px;height:15px}main{max-width:1240px;margin:0 auto;padding:36px 44px 50px;min-height:calc(100vh - 125px)}.page-intro{margin-bottom:28px}.page-intro .eyebrow{margin-bottom:10px}.page-intro p{margin-top:12px;color:var(--muted);font-size:14px;max-width:660px}.hero{background:var(--green);color:#fff;border-radius:18px;padding:30px 34px;display:grid;grid-template-columns:1.3fr 1fr;position:relative;overflow:hidden;min-height:228px;gap:20px}.hero .eyebrow{color:#c8deb3}.hero h2{font-size:34px;color:#fbfdf6;margin:11px 0}.hero p{font-size:12px;color:#c1d2c7;max-width:350px;line-height:1.8;margin-bottom:23px}.hero-chart{align-self:center;position:relative}.hero-chart svg{width:100%;max-height:180px}.hero-chart .caption{position:absolute;right:5px;bottom:6px;font-size:10px;letter-spacing:.06em;color:#a7c1ad}.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:15px;margin:22px 0 31px}.stat{background:var(--paper);border:1px solid var(--line);padding:17px 20px;border-radius:12px;display:flex;align-items:center;justify-content:space-between}.stat .value{font-size:27px;font-weight:600;letter-spacing:-.05em}.stat p{font-size:11px;color:var(--muted)}.stat-icon{width:34px;height:34px;background:var(--mint);border-radius:9px;display:grid;place-items:center;font-size:17px;color:var(--green)}.section-heading{display:flex;align-items:center;justify-content:space-between;gap:15px;margin:23px 0 17px}.section-heading h2{font-size:26px}.section-heading span{font-size:11px;color:var(--muted)}.filters{display:flex;gap:7px;flex-wrap:wrap;margin-bottom:20px}.chip{border:1px solid var(--line);background:transparent;border-radius:30px;padding:7px 14px;font-size:11px;color:#68776c}.chip.active{background:var(--ink);color:white;border-color:var(--ink)}.course-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}.course-card{background:var(--paper);border:1px solid var(--line);border-radius:13px;padding:20px;display:flex;flex-direction:column;min-height:214px;box-shadow:var(--shadow);transition:transform .15s,border-color .15s}.course-card:hover{transform:translateY(-3px);border-color:#adbf9c}.card-top{display:flex;align-items:center;justify-content:space-between;margin-bottom:18px}.section-number{font-family:Georgia,serif;font-size:22px;color:var(--green);background:#eff3e9;border-radius:9px;min-width:43px;height:43px;display:grid;place-items:center;padding:0 8px}.card-tag{font-size:9px;letter-spacing:.04em;border:1px solid var(--line);padding:3px 6px;border-radius:4px;color:var(--muted)}.course-card h3{font-size:15px;margin-bottom:7px}.course-card p{font-size:11px;color:var(--muted);line-height:1.6;margin-bottom:19px}.card-bottom{margin-top:auto;display:flex;justify-content:space-between;align-items:center;font-size:10px;color:var(--muted)}.progress-line{height:3px;background:#edf0e9;border-radius:20px;overflow:hidden;margin:10px 0 0}.progress-line i{display:block;height:100%;background:#6f9566;border-radius:20px}.bottom-callout{margin-top:26px;padding:20px 23px;border:1px solid #dbe4ce;border-radius:12px;background:#edf2e5;display:flex;justify-content:space-between;align-items:center;gap:20px}.bottom-callout p{font-size:12px;color:var(--muted);margin-top:4px}.bottom-callout h3{font-size:14px}.toolbar{display:flex;justify-content:space-between;gap:15px;align-items:center;flex-wrap:wrap;margin:22px 0}.tabs{display:flex;gap:22px;border-bottom:1px solid var(--line);margin:20px 0 25px}.tab{background:none;border:0;border-bottom:2px solid transparent;padding:10px 1px 13px;font-size:12px;color:var(--muted);margin-bottom:-1px}.tab.active{color:var(--green);border-color:var(--green);font-weight:700}.lesson-layout{display:grid;grid-template-columns:minmax(0,1fr) 235px;gap:24px}.lesson-list{display:grid;gap:15px}.lesson-card,.panel{background:var(--paper);border:1px solid var(--line);border-radius:13px;padding:24px}.lesson-card{display:flex;gap:18px}.step-num{flex-shrink:0;font-size:12px;color:#75906d;width:25px;height:25px;border-radius:50%;background:#eff4e9;display:grid;place-items:center}.lesson-card h3{font-size:16px;margin:2px 0 12px}.lesson-card p{font-size:14px;line-height:1.95;color:#536359}.lesson-aside{align-self:start;position:sticky;top:20px}.lesson-aside p{font-size:12px;color:var(--muted);margin:11px 0 18px}.lesson-aside .btn{width:100%}.scope-note{font-size:12px;border-left:3px solid #bcaa6e;padding:10px 14px;background:#f7f3e8;color:#796c41;margin:16px 0}.question-wrap{max-width:820px;margin:0 auto}.q-top{display:flex;justify-content:space-between;align-items:center;margin-bottom:14px;gap:12px}.q-top span{font-size:11px;color:var(--muted)}.q-meter{height:4px;background:#e1e7dc;margin:12px 0 25px;border-radius:20px;overflow:hidden}.q-meter div{height:100%;background:#76a267}.question-card{border:1px solid var(--line);background:#fff;border-radius:16px;padding:30px}.q-meta{display:flex;gap:8px;align-items:center;margin-bottom:17px;font-size:10px;letter-spacing:.04em;color:var(--muted)}.q-meta .pill{padding:4px 8px;border-radius:5px;background:#eff4e9;color:var(--green)}.question-prompt{font-size:20px;line-height:1.85;font-weight:500;margin-bottom:23px;overflow-wrap:anywhere}.question-prompt .katex{font-size:1.13em}.choice-grid{display:grid;gap:10px}.choice{display:flex;gap:13px;align-items:center;text-align:left;background:white;border:1px solid #dce3d7;border-radius:10px;padding:13px 15px;font-size:13px;min-height:52px}.choice:hover{background:#f6f8f2}.choice.selected{border-color:var(--green);background:#eef5e9;box-shadow:0 0 0 1px var(--green)}.choice.correct{border-color:#5d966c;background:#edf7eb}.choice.incorrect{border-color:#c98176;background:#fdf1ed}.choice-letter{width:25px;height:25px;border-radius:6px;border:1px solid #d9e0d4;display:grid;place-items:center;flex-shrink:0;font-size:11px;color:#728169}.answer-label{display:block;font-size:12px;font-weight:650;margin-bottom:7px}.answer-input{padding:13px 15px;border:1px solid #cdd8c8;border-radius:9px;font-size:17px;width:100%;background:#fcfdf9}.syntax-help{font-size:11px;color:var(--muted);margin:8px 0}.syntax-help code{background:#f0f3eb;padding:1px 4px;border-radius:3px}.input-preview{min-height:24px;font-size:12px;color:var(--green);margin:7px 0}.q-actions{display:flex;align-items:center;justify-content:space-between;gap:12px;flex-wrap:wrap;margin-top:23px;border-top:1px solid var(--line);padding-top:20px}.q-actions .left{display:flex;gap:8px}.feedback{border-radius:10px;padding:16px 18px;margin-top:20px;background:#f8efe8;border:1px solid #e8cdb6}.feedback.success{background:#edf5e8;border-color:#cedfc4}.feedback h3{font-size:15px;margin-bottom:5px}.feedback p{font-size:12px}.solution{margin-top:25px}.solution h3{margin-bottom:15px}.solution-step{display:flex;gap:13px;padding:13px 0;border-bottom:1px solid #edf0e8}.solution-step p{font-size:13px;line-height:1.9;flex:1;min-width:0;overflow-wrap:anywhere}.solution-step .text-btn{font-size:10px;white-space:nowrap;align-self:start}.mistake{margin-top:18px;padding:13px 16px;border-left:3px solid #d4b779;background:#faf8ef;font-size:12px;color:#74653e}.hint-box{background:#eef3e8;padding:14px 17px;border-radius:9px;margin:16px 0;font-size:13px}.q-nav{display:flex;justify-content:space-between;gap:10px;margin-top:16px}.example{margin-bottom:20px}.example>summary{font-size:14px;font-weight:600;cursor:pointer}.example .question-prompt{font-size:16px;margin-top:15px}.study-actions{display:flex;gap:10px;margin-top:23px;flex-wrap:wrap}.review-list{display:grid;gap:11px}.review-row{display:flex;gap:15px;align-items:center;background:#fff;border:1px solid var(--line);padding:16px 19px;border-radius:12px}.review-row .review-text{flex:1;min-width:0}.review-row h3{font-size:14px}.review-row p{font-size:11px;color:var(--muted);margin-top:3px}.empty{text-align:center;padding:48px 25px;background:#fff;border:1px solid var(--line);border-radius:15px}.empty h2{margin:16px 0 10px}.empty p{max-width:440px;margin:0 auto 20px;color:var(--muted);font-size:13px}.empty-mark{font-size:32px;color:#739269}.exam-select{display:grid;grid-template-columns:1fr 1fr;gap:8px;margin:18px 0}.check-label{display:flex;align-items:center;gap:9px;font-size:12px;padding:10px;border:1px solid var(--line);border-radius:7px}.check-label input{accent-color:var(--green);width:17px;height:17px}.field{display:grid;gap:5px;margin-bottom:15px;font-size:12px;font-weight:600}.field input,.field select,.field textarea{width:100%;border:1px solid #cdd7c7;border-radius:7px;padding:10px;background:#fff;color:var(--ink);font-size:13px}.field small{font-weight:400;color:var(--muted)}.result-big{font-family:Georgia,serif;font-size:62px;line-height:1;color:var(--green);margin:20px 0}.result-list{margin-top:22px}.result-list details{border-top:1px solid var(--line);padding:13px 0}.result-list summary{font-size:13px;cursor:pointer}.result-list summary span{font-size:11px;color:var(--muted)}.chart{width:100%;height:auto;display:block;border-radius:10px;background:#fafcf7}.chart text{font-family:inherit;font-size:10px;fill:#8b988e}.chart .axis{stroke:#b8c6b9;stroke-width:1}.chart .grid{stroke:#e6ede2;stroke-width:1}.graph-panel{padding:20px;background:#fff;border:1px solid var(--line);border-radius:14px}.graph-key{display:flex;gap:16px;flex-wrap:wrap;font-size:11px;margin:14px 0;color:var(--muted)}.graph-key i{display:inline-block;width:13px;height:3px;margin-right:5px;vertical-align:middle}.graph-controls{display:flex;gap:20px;align-items:end;margin-top:18px;flex-wrap:wrap}.graph-controls .field{flex:1;margin-bottom:0;min-width:150px}input[type=range]{accent-color:var(--green);padding:8px 0}.graph-values{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin-top:17px}.graph-value{border:1px solid var(--line);background:#fafcf7;border-radius:9px;padding:12px;font-size:12px}.graph-value strong{display:block;font-size:20px;margin:5px 0}.formula-grid{display:grid;grid-template-columns:1fr 1fr;gap:16px}.formula-grid .lesson-card{display:block}.formula-grid .lesson-card p{font-size:13px}.tutor{position:fixed;right:0;top:0;bottom:0;width:350px;background:#fff;border-left:1px solid var(--line);z-index:70;display:flex;flex-direction:column;box-shadow:-10px 0 35px #17392a0a}.tutor[hidden]{display:none}.tutor-open .workspace{margin-right:350px}.tutor-head{padding:22px 20px 15px;border-bottom:1px solid var(--line);display:flex;align-items:start;justify-content:space-between}.tutor-head h3{font-family:Georgia,serif;font-size:22px;font-weight:400}.tutor-head p{font-size:10px;color:var(--muted);margin-top:4px}.tutor-tabs{display:flex;gap:20px;padding:0 20px;border-bottom:1px solid var(--line)}.tutor-body{padding:20px;overflow-y:auto;flex:1;min-height:0}.context-label{background:#f0f4ea;border:1px solid #dce5d3;padding:11px 13px;border-radius:8px;font-size:11px;color:#60734f;margin-bottom:18px}.tutor-option{width:100%;text-align:left;background:#fff;border:1px solid var(--line);border-radius:9px;padding:12px;margin:5px 0;font-size:12px;display:flex;justify-content:space-between;align-items:center}.tutor-copy{font-size:12px;line-height:1.9;color:#5a6a5f;margin:13px 0}.chat-msg{font-size:12px;line-height:1.85;border-radius:10px;padding:12px;margin:12px 0;white-space:pre-wrap;overflow-wrap:anywhere}.chat-msg.user{background:#eaf2e3;margin-left:18px}.chat-msg.assistant{background:#f4f6f0;margin-right:8px}.chat-msg.error{background:#fbefeb}.chat-msg .katex{white-space:normal}.chat-form{padding:16px;border-top:1px solid var(--line);background:#fbfcf8}.chat-form textarea{border:1px solid #d8e0d1;border-radius:9px;padding:11px;width:100%;resize:vertical;min-height:75px;font-size:12px}.chat-form .send-row{display:flex;justify-content:space-between;align-items:center;margin-top:8px}.chat-form small{font-size:9px;color:var(--muted)}.offline-note{padding:12px;border:1px solid #ddd8bf;background:#faf7eb;border-radius:8px;font-size:11px;line-height:1.8}.tutor-answer h3{font-size:14px;margin:19px 0 8px}.tutor-answer p{font-size:12px;line-height:1.95;margin-bottom:12px}.tutor-answer .btn{margin-top:13px}.tutor-answer .solution-step{gap:8px}.tutor-answer .solution-step p{font-size:12px}dialog{border:1px solid var(--line);border-radius:18px;padding:30px;width:580px;max-width:calc(100vw - 30px);max-height:90vh;color:var(--ink);box-shadow:0 25px 90px #142f3033}dialog::backdrop{background:#102c2966;backdrop-filter:blur(3px)}.dialog-top{display:flex;justify-content:space-between;align-items:center;margin-bottom:20px}.dialog-top h2{font-size:28px}.settings-section{padding:17px 0;border-top:1px solid var(--line)}.settings-section h3{font-size:14px;margin-bottom:12px}.settings-section p{font-size:12px;color:var(--muted);margin-bottom:13px}.settings-actions{display:flex;gap:9px;flex-wrap:wrap}.settings-message{font-size:12px;color:var(--green);padding:10px 0}#toast{position:fixed;bottom:25px;left:50%;transform:translateX(-50%);z-index:200;background:var(--ink);color:white;border-radius:9px;padding:11px 18px;font-size:12px;box-shadow:var(--shadow);pointer-events:none;opacity:0;transition:opacity .15s;max-width:90vw}#toast.show{opacity:1}footer{font-size:10px;color:#8c978e;border-top:1px solid var(--line);margin:0 44px;padding:17px 0;display:flex;justify-content:space-between;gap:10px}.mobile-top{display:none}.katex{font-size:1.12em}.katex-display{overflow-x:auto;overflow-y:hidden;padding:6px 0}.math-error{font-family:monospace;font-size:12px}.search-wrap{position:relative}.search-wrap input{border:1px solid var(--line);border-radius:8px;background:#fff;padding:9px 12px;font-size:12px;width:210px}.table-wrap{overflow:auto}.quick-table{width:100%;border-collapse:collapse;font-size:13px}.quick-table td,.quick-table th{text-align:left;border-bottom:1px solid var(--line);padding:12px}.quick-table th{font-weight:600;background:#f3f6ee}
@media(min-width:1600px){main{padding-top:45px}.course-card{min-height:235px}}
@media(max-width:1250px){.tutor-open .course-grid{grid-template-columns:1fr 1fr}.tutor-open .hero{grid-template-columns:1fr}.tutor-open .hero-chart{display:none}.tutor-open .lesson-layout{grid-template-columns:1fr}.tutor-open .lesson-aside{position:static}.tutor-open .stats{gap:8px}.tutor-open .stat{padding:12px}.tutor-open .stat-icon{display:none}.tutor-open main{padding:27px}}
@media(max-width:1100px){.sidebar{width:220px;padding:25px 14px}.workspace{margin-left:220px}main{padding:30px}.topbar{padding:0 30px}.course-grid{grid-template-columns:1fr 1fr}.lesson-layout{grid-template-columns:1fr}.lesson-aside{position:static}.hero{padding:28px}.hero h2{font-size:30px}.tutor-open .workspace{margin-right:0}.tutor{box-shadow:-20px 0 80px #17392a30}.question-card{padding:24px}}
@media(max-width:760px){.mobile-top{display:flex;align-items:center;justify-content:space-between;height:62px;padding:0 17px;background:#fcfcf9;border-bottom:1px solid var(--line);position:sticky;top:0;z-index:35}.mobile-brand{font-size:15px;font-weight:650}.sidebar{transform:translateX(-100%);transition:transform .2s;width:260px;z-index:80}.nav-open .sidebar{transform:translateX(0)}#scrim:not([hidden]){display:block;position:fixed;inset:0;background:#14392b55;z-index:75}.workspace{margin-left:0}.topbar{display:none}main{padding:26px 18px 35px}.page-intro h1{font-size:36px}.page-intro p{font-size:13px}.hero{grid-template-columns:1fr;padding:25px;min-height:210px}.hero-chart{display:none}.hero h2{font-size:32px}.stats{gap:8px;margin:16px 0 26px}.stat{padding:13px 11px}.stat .value{font-size:23px}.stat p{font-size:9px}.stat-icon{display:none}.course-grid{gap:11px}.course-card{padding:16px;min-height:221px}.course-card h3{font-size:14px}.course-card p{font-size:11px}.card-tag{font-size:8px}.section-number{font-size:20px;min-width:36px;height:36px}.card-top{margin-bottom:15px}.bottom-callout{align-items:start;flex-direction:column;gap:12px}.section-heading h2{font-size:25px}.section-heading{flex-wrap:wrap}.search-wrap{width:100%}.search-wrap input{width:100%}.toolbar{gap:11px}.tabs{gap:25px}.lesson-card{padding:20px 17px;gap:12px}.lesson-card p{font-size:13px}.question-card{padding:22px 17px}.question-prompt{font-size:17px}.q-actions .left{flex-wrap:wrap}.q-actions{align-items:start}.q-actions .btn{font-size:11px;padding:9px 12px}.solution-step{flex-wrap:wrap}.solution-step p{font-size:12px}.solution-step .text-btn{margin-left:38px}.formula-grid{grid-template-columns:1fr}.graph-values{gap:7px}.graph-value{font-size:10px;padding:9px}.graph-value strong{font-size:17px}.tutor{width:min(100vw,390px)}.tutor-open main{padding:26px 18px}.exam-select{grid-template-columns:1fr}.review-row{flex-wrap:wrap}.review-row .btn{margin-left:58px}.question-wrap{width:100%}.q-top{flex-wrap:wrap}.lesson-layout{gap:16px}footer{margin:0 18px;font-size:9px;flex-direction:column;gap:2px}.scope-note{font-size:11px}dialog{padding:22px}.graph-panel{padding:13px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important;animation:none!important}}
@media print{.sidebar,.topbar,.mobile-top,.tutor,.tabs,.btn,.text-btn,footer,#toast{display:none!important}.workspace{margin:0!important}main{padding:0}.lesson-layout{display:block}.lesson-card{break-inside:avoid;box-shadow:none}.lesson-aside{display:none}.page-intro h1{font-size:30px}}

@media(max-width:760px){.sidebar{visibility:hidden}.nav-open .sidebar{visibility:visible}}
