:root{--bg:#edf3f8;--paper:#fff;--ink:#172033;--muted:#5f6f82;--line:#d6e0ea;--blue:#0f5bd5;--violet:#5940c7;--green:#0b8b72;--shadow:0 12px 30px rgba(35,54,80,.09);--radius:18px}
*{box-sizing:border-box;min-width:0}html,body{margin:0;width:100%;max-width:100%;overflow-x:hidden;overflow-x:clip}body{font-family:Inter,ui-sans-serif,system-ui,-apple-system,"Segoe UI",Arial,sans-serif;background:linear-gradient(135deg,#edf5ff,#f6f3ff,#ecfaf6);color:var(--ink);line-height:1.65}img,svg,video,iframe{max-width:100%}a{color:var(--blue)}button,input{font:inherit}.page-shell{width:min(1220px,calc(100% - 20px));margin:auto;padding:10px 0 24px}
.site-header{display:flex;align-items:center;justify-content:space-between;gap:14px;background:rgba(255,255,255,.95);border:1px solid var(--line);border-radius:18px;padding:8px 12px;box-shadow:var(--shadow);position:relative;z-index:60}.brand{display:flex;align-items:center;text-decoration:none;flex:0 0 auto}.brand img{width:160px;height:80px;object-fit:contain;display:block}.desktop-nav{display:flex;flex-wrap:wrap;justify-content:flex-end;gap:3px 7px}.desktop-nav a{padding:7px 6px;border-radius:8px;text-decoration:none;color:#24344e;font-size:.88rem;font-weight:800}.desktop-nav a:hover,.desktop-nav .active{background:#edf4ff;color:#0f56c5}.site-menu-btn{display:none;width:44px;height:44px;border:1px solid #cbd7e5;border-radius:11px;background:#fff;align-items:center;justify-content:center;font-size:1.35rem;font-weight:900;cursor:pointer}.mobile-nav{display:none;margin:7px 0;background:#fff;border:1px solid var(--line);border-radius:14px;padding:7px;box-shadow:var(--shadow);position:relative;z-index:59}.mobile-nav.open{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:5px}.mobile-nav a{padding:9px;border-radius:8px;text-decoration:none;background:#f5f8fc;color:#25324a;font-weight:800;text-align:center}
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.toolbar{display:flex;gap:6px;flex-wrap:wrap;margin:7px 0}.toolbar button,.chapter-menu-btn{border:1px solid #c8d6e6;background:#fff;border-radius:9px;padding:8px 11px;font-weight:850;color:#24344e;cursor:pointer}.chapter-menu-btn{display:flex;align-items:center;justify-content:center;position:sticky;top:4px;z-index:52;width:100%;margin:6px 0;box-shadow:0 8px 20px rgba(37,57,84,.08)}
.chapter-drawer{position:fixed;top:0;left:0;width:min(370px,90vw);height:100dvh;background:#fff;z-index:1002;padding:14px;overflow:auto;transform:translateX(-105%);transition:transform .22s ease;box-shadow:14px 0 40px rgba(0,0,0,.2)}.chapter-drawer.open{transform:none}.drawer-top{display:flex;justify-content:space-between;align-items:center;gap:8px;position:sticky;top:0;background:#fff;padding:4px 0 9px;z-index:2}.drawer-top button{border:1px solid #d1dbe6;border-radius:8px;background:#fff;width:38px;height:38px;cursor:pointer}.chapter-search-label{display:block;font-weight:900;font-size:.82rem}.chapter-search{width:100%;padding:9px 10px;border:1px solid #cbd7e5;border-radius:9px;margin:5px 0 10px}.chapter-list h3{font-size:.82rem;text-transform:uppercase;letter-spacing:.05em;color:#68788c;margin:14px 3px 6px}.chapter-list a{display:grid;grid-template-columns:52px 1fr;gap:6px;text-decoration:none;color:#25324a;padding:8px;border-radius:9px;border:1px solid transparent}.chapter-list a:hover,.chapter-list a.current{background:#edf4ff;border-color:#c8dcf7}.chapter-list span{font-size:.78rem;color:#637286}.chapter-list b{font-size:.86rem}.chapter-overlay{position:fixed;inset:0;background:rgba(10,20,35,.52);z-index:1001;opacity:0;pointer-events:none;transition:opacity .2s}.chapter-overlay.show{opacity:1;pointer-events:auto}body.drawer-open{overflow:hidden}
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.site-footer{margin-top:18px;background:#152033;color:#fff;border-radius:22px;padding:24px 18px}.footer-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:18px}.footer-grid>div{display:flex;flex-direction:column;gap:7px}.footer-grid strong{font-size:1rem}.footer-grid a{color:#e6eef9;text-decoration:none;font-weight:750}.social-row{display:flex;justify-content:center;gap:8px;flex-wrap:wrap;margin:18px 0 10px}.social-row a{width:34px;height:34px;display:inline-flex;align-items:center;justify-content:center;background:#fff;border-radius:50%;text-decoration:none}.social-row svg{width:17px;height:17px;fill:currentColor}.social-row a:nth-child(1){color:#1877f2}.social-row a:nth-child(2){color:#e4405f}.social-row a:nth-child(3){color:#111}.social-row a:nth-child(4){color:#f00}.social-row a:nth-child(5){color:#111}.social-row a:nth-child(6){color:#08c}.copyright,.independent-note{text-align:center;color:#d7e3f2;margin:7px auto}.independent-note{max-width:900px;font-size:.82rem}
body.night{--ink:#eef5ff;--muted:#c0cada;--line:#354259;background:#101622}.night .panel,.night .lesson,.night .site-header,.night .mobile-nav,.night .translate-bar,.night .chapter-card,.night .toolbar button,.night .chapter-menu-btn{background:#171f2d;color:#eef5ff}.night .desktop-nav a,.night .mobile-nav a,.night .chapter-card,.night .chapter-list a{color:#e8f0fb}.night .analogy,.night .example,.night .steps,.night .mistakes,.night .practice{background:#1c2736;color:#eef5ff}.night .chapter-drawer{background:#171f2d;color:#eef5ff}.night .drawer-top{background:#171f2d}
[dir=rtl] body{text-align:right}[dir=rtl] .chapter-drawer{left:auto;right:0;transform:translateX(105%)}[dir=rtl] .chapter-drawer.open{transform:none}[dir=rtl] .lesson ol,[dir=rtl] .lesson ul{padding-left:0;padding-right:1.3rem}[dir=rtl] .analogy,[dir=rtl] .example,[dir=rtl] .steps,[dir=rtl] .mistakes,[dir=rtl] .practice{border-left:0;border-right:4px solid #aac8ef}
.certificate-page{min-height:100vh;display:grid;place-items:center;padding:20px;background:#eef4fb}.certificate-card{width:min(1000px,100%);background:#fff;border:12px double #1e4678;padding:50px;text-align:center}.certificate-card img{width:220px}.cert-kicker{text-transform:uppercase;letter-spacing:.16em;font-weight:900;color:#53677e}.certificate-card h1{font-size:clamp(2rem,6vw,4rem);margin:.5rem 0}.name-line{margin:28px auto;border-bottom:2px solid #203a5a;width:min(620px,90%);font-size:2rem;padding:10px}.cert-grid{display:grid;grid-template-columns:1fr 1fr;gap:20px;margin:25px 0}.cert-grid div{display:flex;flex-direction:column}.cert-disclaimer{font-size:.85rem;color:#596b80}.certificate-card button,.certificate-card a{display:inline-block;margin:8px;padding:9px 14px;border-radius:8px;border:1px solid #b9c9da;background:#fff;text-decoration:none;color:#173d70;font-weight:800}
@media(max-width:1050px){.desktop-nav{display:none}.site-menu-btn{display:flex}.brand img{width:135px;height:auto}.footer-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.card-grid{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media(max-width:700px){.page-shell{width:min(100% - 10px,1220px)}.site-header{padding:6px 8px}.brand img{width:118px}.site-menu-btn{width:40px;height:40px}.translate-bar{min-height:30px;padding:2px 5px;margin:4px 0}.translate-bar small{display:none}.hero{padding:22px 16px;border-radius:18px}.hero h1{font-size:clamp(1.75rem,9vw,2.7rem)}.jump-grid{grid-template-columns:1fr}.panel,.lesson{padding:16px;border-radius:14px}.card-grid{grid-template-columns:1fr}.pager{grid-template-columns:1fr 1fr}.pager a:nth-child(2){grid-column:1/-1;grid-row:2}.footer-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}.social-row a{width:32px;height:32px}.social-row svg{width:16px;height:16px}.certificate-card{padding:25px 14px;border-width:7px}.cert-grid{grid-template-columns:1fr}}
@media(max-width:390px){.brand img{width:104px}.mobile-nav.open{grid-template-columns:1fr}.footer-grid{grid-template-columns:1fr 1fr}.footer-grid a{font-size:.84rem}.chapter-drawer{width:92vw}}
@media print{.site-header,.mobile-nav,.translate-bar,.toolbar,.chapter-menu-btn,.chapter-drawer,.chapter-overlay,.site-footer{display:none!important}.page-shell,.content{width:100%!important}.panel,.lesson{box-shadow:none;break-inside:avoid}.certificate-page{padding:0;background:#fff}}