:root{color-scheme:dark;--bg:#101820;--surface:#19232d;--surface2:#202d38;--line:#33414d;--text:#eef5f3;--muted:#adbac2;--accent:#9bedc4;--accent2:#68d6b0}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:radial-gradient(circle at 80% -15%,#214c46 0,transparent 37%),var(--bg);color:var(--text);font:16px/1.55 system-ui,-apple-system,Segoe UI,sans-serif}button,a{font:inherit}button{cursor:pointer}a{color:inherit;text-decoration:none}.topbar{min-height:72px;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;gap:20px;padding:12px max(24px,calc((100vw - 1200px)/2));background:#111923e8;position:sticky;top:0;z-index:5;backdrop-filter:blur(12px)}.brand{display:inline-flex;align-items:center;gap:12px;font-size:1.25rem;font-weight:700;white-space:nowrap}.brand b{color:var(--accent)}.brand-mark{display:grid;place-items:center;width:42px;height:42px;border-radius:13px;background:var(--accent);color:#10231d;font-size:27px}.topnav{display:flex;gap:12px;align-items:center}.topnav a,.topnav button{border:1px solid var(--line);border-radius:10px;background:var(--surface);padding:8px 12px;color:var(--text)}.topnav a:hover,.topnav button:hover{border-color:var(--accent2)}.app{max-width:1200px;margin:auto;padding:44px 24px 80px;min-height:calc(100vh - 130px)}.eyebrow{text-transform:uppercase;letter-spacing:.18em;color:var(--accent);font-size:.76rem;font-weight:800}.hero{padding:18px 0 34px}.hero h1,.pagehead h1{font-size:clamp(2rem,5vw,4rem);line-height:1.08;letter-spacing:-.045em;margin:12px 0}.hero p,.pagehead p{color:var(--muted);font-size:1.08rem;max-width:700px}.stats{display:flex;flex-wrap:wrap;gap:14px;margin-top:26px}.stat{border:1px solid var(--line);background:#1b2931b3;border-radius:14px;padding:12px 17px;min-width:130px}.stat b{display:block;color:var(--accent);font-size:1.25rem}.stat span{color:var(--muted);font-size:.8rem}.topic-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(245px,1fr));gap:16px}.topic-card,.panel,.type-card,.exercise-card{border:1px solid var(--line);background:var(--surface);border-radius:18px}.topic-card{display:flex;flex-direction:column;min-height:215px;padding:23px;transition:transform .18s,border-color .18s}.topic-card:hover{transform:translateY(-3px);border-color:var(--accent2)}.topic-icon{color:var(--accent);font-size:1.65rem;font-weight:800}.topic-card h2{margin:12px 0 6px;font-size:1.35rem}.topic-card p{color:var(--muted);margin:0 0 14px;font-size:.92rem;flex:1}.topic-card small{color:var(--accent)}.back{display:inline-flex;color:var(--accent);margin-bottom:22px}.pagehead{margin-bottom:26px}.pagehead h1{font-size:clamp(2rem,4vw,3.2rem)}.section-title{font-size:1.32rem;margin:32px 0 14px}.study-grid{display:grid;grid-template-columns:minmax(0,1.2fr) minmax(260px,.8fr);gap:16px}.panel{padding:23px}.panel h2{margin:0 0 12px;font-size:1.18rem}.panel ul{padding-left:22px;margin:0}.panel li{margin:10px 0}.example-steps{padding-left:22px;margin:0}.example-steps li{padding:5px 0}.type-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:14px}.type-card{padding:20px;display:flex;flex-direction:column}.type-card h3{margin:0 0 6px}.type-card p{color:var(--muted);flex:1;margin:0 0 16px}.type-card small{display:block;color:var(--accent);margin-bottom:12px}.primary,.secondary{border-radius:10px;padding:11px 16px;font-weight:700}.primary{background:var(--accent);border:1px solid var(--accent);color:#0c211b}.primary:hover{background:#c0f5db}.secondary{background:transparent;border:1px solid var(--line);color:var(--text)}.secondary:hover{border-color:var(--accent2)}.toolbar{display:flex;flex-wrap:wrap;align-items:center;gap:12px;margin:18px 0 22px}.toolbar label{color:var(--muted)}select{background:var(--surface2);border:1px solid var(--line);border-radius:9px;color:var(--text);padding:10px}.counter{color:var(--muted);margin-left:auto}.exercise-card{padding:clamp(22px,4vw,40px)}.exercise-meta{color:var(--accent);font-size:.84rem;font-weight:800;letter-spacing:.06em;text-transform:uppercase}.question{font-size:clamp(1.3rem,3vw,2rem);font-weight:700;line-height:1.38;margin:24px 0 28px;white-space:normal}.exercise-actions{display:flex;flex-wrap:wrap;gap:10px}.solution{margin-top:28px;border-top:1px solid var(--line);padding-top:20px}.solution h3{margin:0 0 14px;color:var(--accent)}.solution ol{margin:0 0 20px;padding-left:24px}.solution li{margin:10px 0;padding-left:5px}.answer{background:#123e35;border:1px solid #32775c;border-radius:12px;padding:14px 18px;font-weight:700}.progress{height:8px;border-radius:8px;background:#35444d;overflow:hidden;margin:22px 0}.progress span{display:block;height:100%;background:var(--accent);transition:width .2s}.hint{color:var(--muted);font-size:.88rem}footer{border-top:1px solid var(--line);padding:24px;text-align:center;color:var(--muted);font-size:.85rem}@media(max-width:680px){.topbar{padding:10px 16px}.topnav a{display:none}.app{padding:28px 16px 60px}.study-grid{grid-template-columns:1fr}.counter{margin-left:0;width:100%}.topic-grid{grid-template-columns:1fr}.topic-card{min-height:0}.exercise-actions button{flex:1}}
.topic-diagram{display:block;width:100%;height:auto;max-height:230px;margin:18px 0 32px;border-radius:20px}.concept-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px}.concept-card{border:1px solid var(--line);background:linear-gradient(145deg,#1a2b32,#19232d);border-radius:18px;padding:24px;min-width:0}.concept-card h3,.visual-step h3{margin:3px 0 12px;font-size:1.12rem}.concept-card p,.visual-step p{color:var(--muted);margin:14px 0 0;line-height:1.65}.step-number{color:var(--accent);font-size:.8rem;font-weight:900;letter-spacing:.14em}.math-image{display:block;max-width:100%;overflow-x:auto;overflow-y:hidden;padding:14px 12px;border:1px solid #42655e;background:#112826;border-radius:11px;color:#f4fffa;font-size:1.55rem;text-align:center}.math-image mjx-container{display:block!important;margin:.12em auto!important;width:max-content;max-width:none}.math-image svg{max-width:none}.math-fallback{font-family:Cambria Math,Georgia,serif;font-size:1rem;white-space:normal}.math-image.is-rendered .math-fallback{display:none}.worked-example,.solution-steps{display:grid;gap:12px}.visual-step{display:grid;grid-template-columns:44px minmax(0,1fr);gap:14px;border:1px solid var(--line);background:var(--surface);border-radius:16px;padding:19px 23px}.visual-step .step-number{border:1px solid #4b7467;background:#153a34;border-radius:11px;width:38px;height:38px;display:grid;place-items:center}.visual-step-body{min-width:0}.step-formula{color:#f4fffa;background:#1a3132}.question-board{margin:22px 0 26px;border:1px solid #4b7467;background:linear-gradient(135deg,#14342f,#1b2d33);border-radius:16px;padding:24px}.question-board p{font-size:1.14rem;line-height:1.5;margin:9px 0 18px}.board-label{display:block;color:var(--accent);font-size:.76rem;font-weight:900;letter-spacing:.17em}.question-formula{font-size:2rem;padding:25px 15px}.solution-intro{padding:18px 20px;border:1px solid var(--line);border-radius:14px;background:#202f38;margin-bottom:18px}.solution-intro h3{margin:5px 0;color:var(--text)}.solution-intro p{margin:0;color:var(--muted)}.solution .visual-step p{margin:4px 0 11px}.solution .step-formula{font-size:1.3rem}.answer{margin-top:18px}.answer .math-image{margin:10px 0;background:#17473b;border-color:#50a783;font-size:1.8rem}.answer p{margin:5px 0 0;font-weight:500;color:#d1ede1}.type-card button{align-self:flex-start}.type-card small{color:#a7ebca}@media(max-width:680px){.concept-grid{grid-template-columns:1fr}.concept-card{padding:19px}.visual-step{grid-template-columns:34px minmax(0,1fr);padding:15px;gap:10px}.visual-step .step-number{width:32px;height:32px}.question-board{padding:17px}.math-image{font-size:1.25rem}.question-formula{font-size:1.4rem}.topic-diagram{margin:8px 0 20px}}
.math-image mjx-assistive-mml{position:absolute!important;top:0!important;left:0!important;width:1px!important;height:1px!important;overflow:hidden!important;clip:rect(1px,1px,1px,1px)!important;white-space:nowrap!important}