:root{--bg:#071525;--panel:#0d2033;--panel2:#112a40;--line:#244257;--text:#f4fbff;--muted:#9cb4c2;--cyan:#54dff1;--teal:#16c7ad;--lime:#c8f064;--coral:#ff6f78;--violet:#a990ff;--paper:#f6f2e8;--ink:#102638;--shadow:0 24px 70px rgba(0,0,0,.28);--radius:24px;--font-scale:1}
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.self-check{margin-top:22px;padding:18px;border-radius:18px;border:1px solid var(--line);background:rgba(255,255,255,.025)}.self-check h3{margin:0 0 13px}.option-list{display:grid;gap:8px}.option-list button{padding:12px 14px;border:1px solid var(--line);border-radius:12px;background:var(--panel2);text-align:left;cursor:pointer}.option-list button:hover{border-color:var(--cyan)}.option-list button.correct{border-color:var(--lime);background:rgba(200,240,100,.12)}.option-list button.wrong{border-color:var(--coral);background:rgba(255,111,120,.1)}.feedback{min-height:24px;margin-top:9px;font-size:13px;color:var(--muted)}
.tool-page{padding:52px clamp(28px,6vw,80px)}.tool-hero{display:flex;justify-content:space-between;gap:24px;align-items:end;margin-bottom:30px}.tool-hero h1{margin:8px 0 0;font-size:clamp(38px,5vw,64px);letter-spacing:-.045em}.tool-hero p{max-width:520px;color:var(--muted)}.lab-tabs{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:18px}.lab-tabs button{padding:10px 13px;border:1px solid var(--line);border-radius:12px;background:var(--panel);cursor:pointer}.lab-tabs button.active{background:var(--cyan);color:#072032;border-color:var(--cyan);font-weight:900}.lab-workspace{padding:24px;border:1px solid var(--line);border-radius:24px;background:rgba(13,32,51,.86)}.quiz-shell{max-width:900px}.quiz-progress{height:7px;background:var(--line);border-radius:9px;overflow:hidden;margin:18px 0 30px}.quiz-progress i{display:block;height:100%;width:0;background:linear-gradient(90deg,var(--cyan),var(--lime));transition:.3s}.quiz-card{padding:28px;border:1px solid var(--line);border-radius:24px;background:var(--panel)}.quiz-card h2{font-size:28px}.quiz-meta{display:flex;justify-content:space-between;color:var(--muted);font-size:12px}.quiz-result{padding:34px;border:1px solid var(--line);border-radius:24px;background:linear-gradient(145deg,var(--panel),rgba(169,144,255,.1));text-align:center}.score-orb{width:140px;height:140px;margin:20px auto;border-radius:50%;display:grid;place-items:center;background:conic-gradient(var(--lime) var(--score),rgba(255,255,255,.08) 0);position:relative}.score-orb:before{content:"";position:absolute;inset:10px;background:var(--panel);border-radius:50%}.score-orb span{z-index:1;font-size:32px;font-weight:900}.teacher-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:14px}.metric{padding:18px;border:1px solid var(--line);border-radius:17px;background:var(--panel)}.metric small,.metric strong{display:block}.metric small{color:var(--muted)}.metric strong{font-size:30px;color:var(--cyan)}.teacher-panels{display:grid;grid-template-columns:1fr 1fr;gap:18px;margin-top:18px}.teacher-panel{padding:23px;border:1px solid var(--line);border-radius:22px;background:var(--panel)}.teacher-panel h2{margin-top:0}.progress-list{display:grid;gap:10px}.progress-row{display:grid;grid-template-columns:155px 1fr 38px;gap:10px;align-items:center;font-size:12px}.mini-track{height:8px;border-radius:8px;background:#081827;overflow:hidden}.mini-track i{display:block;height:100%;background:linear-gradient(90deg,var(--cyan),var(--lime))}.export-actions{display:flex;flex-wrap:wrap;gap:9px;margin-top:18px}.export-actions button{padding:10px 13px;border:1px solid var(--line);border-radius:11px;background:var(--panel2);cursor:pointer}.about-grid{display:grid;grid-template-columns:1.25fr .75fr;gap:18px}.about-card{padding:27px;border:1px solid var(--line);border-radius:22px;background:var(--panel)}.about-card h2{margin-top:0}.source-card{background:var(--paper);color:var(--ink)}.source-card .book-spine{width:100%;height:9px;border-radius:9px;background:linear-gradient(90deg,#20a8dd,#83d8ef)}.source-card cite{display:block;margin:20px 0;font-style:normal;font-family:Georgia,serif;font-size:20px}.value-list{display:grid;gap:10px}.value-item{display:grid;grid-template-columns:35px 1fr;gap:10px}.value-item span{width:32px;height:32px;border-radius:10px;display:grid;place-items:center;background:rgba(84,223,241,.12);color:var(--cyan)}.value-item b,.value-item small{display:block}.value-item small{color:var(--muted)}
.search-modal{position:fixed;inset:0;z-index:200;display:none;padding:10vh 20px;background:rgba(3,10,18,.72);backdrop-filter:blur(12px)}.search-modal.open{display:block}.search-box{width:min(720px,100%);max-height:75vh;margin:auto;border:1px solid var(--line);border-radius:22px;background:#0b1d2f;box-shadow:var(--shadow);overflow:hidden}.search-input-wrap{display:grid;grid-template-columns:30px 1fr 35px;align-items:center;padding:16px 18px;border-bottom:1px solid var(--line)}.search-input-wrap input{border:0;outline:0;background:transparent;color:var(--text);font-size:19px}.search-input-wrap button{border:0;background:transparent;color:var(--muted);font-size:22px;cursor:pointer}.search-results{padding:10px;max-height:52vh;overflow-y:auto}.search-result{display:flex;justify-content:space-between;gap:18px;padding:13px;border-radius:13px;cursor:pointer}.search-result:hover,.search-result.selected{background:rgba(84,223,241,.09)}.search-result b,.search-result small{display:block}.search-result small{color:var(--muted)}.search-result span{color:var(--cyan);font-size:11px}.search-hint{display:block;padding:10px 18px;color:var(--muted);border-top:1px solid var(--line)}.toast{position:fixed;right:22px;bottom:24px;z-index:300;padding:12px 16px;border-radius:12px;background:var(--lime);color:#0b2130;font-weight:800;transform:translateY(120px);opacity:0;transition:.3s}.toast.show{transform:none;opacity:1}.global-footer{display:flex;justify-content:space-between;gap:20px;padding:18px 28px;margin-left:290px;border-top:1px solid var(--line);color:var(--muted);font-size:10px;letter-spacing:.08em}
body.light{--bg:#edf3f2;--panel:#fffdf8;--panel2:#e9f2f1;--line:#c9d9d8;--text:#102638;--muted:#5d747c;--shadow:0 24px 70px rgba(28,57,67,.14)}body.light .topbar{background:rgba(239,246,245,.9)}body.light .sidebar{background:rgba(240,247,246,.75)}body.light .equation-board,body.light .sim-panel,body.light .note-area{background:#102638;color:#f5fbff}body.light .progress-ring:before{background:var(--panel)}
@keyframes spin{to{transform:rotate(360deg)}}
@media(max-width:1050px){.topbar{grid-template-columns:250px 1fr}.school-lockup{display:none}.chapter-grid{grid-template-columns:1fr 1fr}.quick-grid{grid-template-columns:1fr 1fr}.quick-grid .quick-card:first-child{grid-column:1/-1}.lesson-layout{grid-template-columns:1fr}.lesson-side{display:grid;grid-template-columns:repeat(2,1fr)}.teacher-grid{grid-template-columns:repeat(2,1fr)}}
@media(max-width:760px){.topbar{height:70px;grid-template-columns:auto 1fr auto;padding:0 13px}.mobile-only{display:grid}.brand-mark{width:38px;height:38px}.brand>span:last-child{display:none}.search-trigger span:nth-child(2),.search-trigger kbd{display:none}.search-trigger{min-width:44px;padding:0;justify-content:center}.app-shell{display:block}.sidebar{position:fixed;z-index:120;top:70px;left:0;width:min(330px,88vw);height:calc(100vh - 70px);transform:translateX(-105%);transition:.25s;background:var(--bg);box-shadow:var(--shadow)}.sidebar.open{transform:none}.hero{padding:55px 22px 42px;min-height:570px}.hero h1{font-size:53px}.hero-visual{width:240px;height:240px;right:-80px;top:300px;opacity:.55}.formula-ribbon{grid-template-columns:1fr 1fr}.section-wrap,.lesson-page,.tool-page{padding:42px 20px}.chapter-grid,.quick-grid,.sim-grid,.teacher-panels,.about-grid{grid-template-columns:1fr}.quick-grid .quick-card:first-child{grid-column:auto}.author-strip{align-items:flex-start;flex-direction:column}.author-strip>span{text-align:left}.lesson-top{display:block}.lesson-actions{margin-top:18px}.outcomes{grid-template-columns:1fr}.lesson-side{grid-template-columns:1fr}.tool-hero{display:block}.teacher-grid{grid-template-columns:1fr 1fr}.progress-row{grid-template-columns:110px 1fr 35px}.global-footer{margin-left:0;display:block;padding:16px 20px}.global-footer span{display:block;margin:3px 0}.chapter-card{min-height:260px}}
@media(max-width:430px){.hero h1{font-size:44px}.chapter-grid,.teacher-grid{grid-template-columns:1fr}.lesson-top h1{font-size:38px}.formula-ribbon strong{font-size:18px}.check-grid{grid-template-columns:1fr}.lesson-pager{flex-direction:column}.lesson-pager button{max-width:none}.top-actions{gap:4px}.icon-btn,.search-trigger{min-width:40px}}
@media print{.topbar,.sidebar,.lesson-actions,.lesson-side,.lesson-pager,.global-footer,.ambient,.interactive-zone{display:none!important}.app-shell{display:block}.view{display:none!important}.view.active{display:block!important}main{padding:0}.lesson-page,.tool-page{padding:20px;color:#111}.content-card,.teacher-panel,.metric{background:#fff;color:#111;border-color:#ccc}.equation-board{background:#eee;color:#111}.lesson-layout{display:block}}
@media(prefers-reduced-motion:reduce){*,*:before,*:after{animation:none!important;scroll-behavior:auto!important;transition:none!important}}