:root{--navy:#173f5f;--blue:#206a9b;--pale:#edf5fa;--paper:#fff;--bg:#f4f7f9;--text:#1f2933;--muted:#637381;--line:#d7e1e8;--orange:#bd5d24;--orange-bg:#fff4ec;--green:#28784d;--green-bg:#ecf8f0;--danger:#9f3a38;--shadow:0 5px 20px rgba(23,63,95,.08);--radius:16px}
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9px;border-radius:99px;background:var(--pale);color:var(--blue);font-size:.78rem;font-weight:800}.concept-card h2{margin:7px 0 8px;color:var(--navy);font-size:1.38rem;line-height:1.35}.idea{margin:0 0 15px}.example,.practice,.solution{margin-top:12px;padding:15px 17px;border-radius:12px}.example{background:var(--orange-bg);border-left:5px solid var(--orange)}.practice{background:#f1f5f8;border-left:5px solid #718696}.solution{background:var(--green-bg);border-left:5px solid var(--green)}.example h3,.practice h3,.solution h3{margin:0 0 5px;font-size:.9rem;letter-spacing:.04em}.example h3{color:var(--orange)}.practice h3{color:#4a6170}.solution h3{color:var(--green)}.question{margin:2px 0;font-weight:700;overflow-wrap:anywhere}.concept-card ol{margin:7px 0 0;padding-left:1.4em}.concept-card li{margin:3px 0}.mistake{margin-top:12px;padding:10px 13px;border-radius:9px;background:#fff0f0;color:var(--danger);font-size:.9rem}.pager{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin-top:24px}.pager a{display:flex;flex-direction:column;padding:14px 16px;border:1px solid var(--line);border-radius:12px;background:#fff;color:var(--navy);text-decoration:none;font-weight:700}.pager a:last-child{text-align:right}.pager small{color:var(--muted);font-weight:400}.scroll-progress{position:fixed;z-index:60;top:60px;left:0;width:0;height:3px;background:#f0b44d}.overlay{position:fixed;z-index:35;inset:60px 0 0;background:#0008}.hero{padding:64px 20px 45px;color:#fff;background:linear-gradient(140deg,#123a58,#2476a9)}.hero-inner{max-width:1050px;margin:auto}.eyebrow{margin:0;font-weight:700;color:#bce1f5}.hero h1{margin:5px 0;font-size:clamp(2.1rem,7vw,4rem);line-height:1.15}.hero>div>p:not(.eyebrow){max-width:650px}.search-wrap{max-width:560px;margin-top:25px}.search-wrap label{display:block;margin-bottom:5px;font-weight:700}.search-wrap input{width:100%;min-height:50px;padding:10px 15px;border:2px solid 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0;color:var(--muted);font-size:.88rem;line-height:1.5}.unit-card small{color:var(--green)}.no-result{text-align:center;color:var(--muted)}footer{padding:25px;text-align:center;color:var(--muted);background:#e9eff3}
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@media(min-width:851px){.menu-button{display:none}}
@media(max-width:430px){body{font-size:15.5px}.topbar{padding:0 10px}.lesson{padding-left:10px;padding-right:10px}.lesson-head h1{font-size:1.65rem}.concept-card h2{font-size:1.22rem}.concept-card{border-radius:12px}.example,.practice,.solution{margin-left:-3px;margin-right:-3px}.hero{padding-left:16px;padding-right:16px}.map{padding-left:12px;padding-right:12px}.unit-card{padding:14px}.unit-number{flex-basis:38px;height:38px}}
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