:root{--ink:#17152d;--muted:#6e6b7e;--paper:#f6f4ed;--violet:#7356e8;--lime:#d8f56d;--line:#dcd8cc;--white:#fffdf7}*{box-sizing:border-box}html{scroll-behavior:smooth}body{background:var(--paper);color:var(--ink);margin:0;font-family:Tahoma,Arial,sans-serif}a{color:inherit;text-decoration:none}.shell{width:min(1180px,100% - 48px);margin-inline:auto}.header{border-bottom:1px solid var(--line);justify-content:space-between;align-items:center;height:92px;display:flex}.header.compact{height:78px}.logo{align-items:center;gap:11px;display:flex}.logo>span{background:var(--ink);width:43px;height:43px;color:var(--lime);border-radius:13px 13px 4px;place-items:center;font:700 22px Georgia;display:grid;box-shadow:0 8px 22px #17152d22}.logo div{flex-direction:column;gap:3px;display:flex}.logo strong{font-size:15px}.logo small{color:var(--muted);font-size:8px}nav{color:#4e4b61;gap:29px;font-size:11px;display:flex}nav a:hover{color:var(--violet)}.header-cta{border:1px solid var(--ink);border-radius:9px;padding:11px 16px;font-size:9px;font-weight:700}.hero{grid-template-columns:1.08fr .92fr;align-items:center;gap:75px;min-height:650px;padding:76px 0 82px;display:grid}.kicker{color:var(--violet);align-items:center;gap:10px;font-size:10px;font-weight:700;display:flex}.kicker span{background:#e5defd;border-radius:20px;padding:5px 8px}.hero h1{letter-spacing:-3.4px;margin:20px 0;font-size:clamp(47px,5.7vw,76px);line-height:1.35}.hero h1 em{color:var(--violet);font-style:normal;position:relative}.hero h1 em:after{content:"";background:repeating-linear-gradient(90deg,var(--lime) 0 11px,transparent 11px 17px);opacity:.9;height:7px;position:absolute;bottom:-4px;left:0;right:0}.hero-copy>p:not(.kicker){max-width:650px;color:var(--muted);margin:0;font-size:14px;line-height:2.1}.hero-actions{align-items:center;gap:22px;margin-top:30px;font-size:10px;font-weight:700;display:flex}.primary{background:var(--ink);color:#fff;border-radius:10px;align-items:center;gap:35px;width:fit-content;padding:13px 18px;font-size:10px;font-weight:700;display:flex}.primary b{color:var(--lime);font-size:16px}.hero-proof{border-top:1px solid var(--line);gap:44px;margin-top:45px;padding-top:22px;display:flex}.hero-proof div{flex-direction:column;gap:4px;display:flex}.hero-proof strong{font:700 20px Arial}.hero-proof span{color:var(--muted);font-size:8px}.math-board{background:var(--ink);color:#fff;border-radius:25px;min-height:490px;padding:26px 28px 24px;position:relative;overflow:hidden;box-shadow:0 35px 70px #312c5c33}.math-board:before{content:"";background-image:linear-gradient(#ffffff09 1px,#0000 1px),linear-gradient(90deg,#ffffff09 1px,#0000 1px);background-size:24px 24px;position:absolute;inset:0}.board-head,.equation,.steps,.axis,.math-board>small{z-index:1;position:relative}.board-head{align-items:center;display:flex}.board-head span{color:#aaa6bd;margin-left:auto;font-size:9px}.board-head i{background:#57536b;border-radius:50%;width:6px;height:6px;margin-right:6px}.board-head i:first-of-type{background:var(--lime)}.equation{text-align:left;color:var(--lime);direction:ltr;margin:38px 0 30px;font:700 29px Georgia}.steps{gap:8px;display:grid}.steps p{background:#ffffff06;border:1px solid #ffffff12;border-radius:10px;grid-template-columns:27px 1fr auto;align-items:center;margin:0;padding:12px;display:grid}.steps p.active{background:var(--violet);border-color:#0000}.steps b{color:var(--lime);font:700 9px Arial}.steps span{font-size:9px}.steps code{color:#d4d0df;direction:ltr;font:12px Georgia}.axis{width:150px;height:112px;position:absolute;bottom:54px;left:32px}.x-axis,.y-axis{background:#ffffff2c;position:absolute}.x-axis{height:1px;top:60px;left:0;right:0}.y-axis{width:1px;top:0;bottom:0;left:72px}.curve{border-bottom:3px solid var(--lime);border-radius:0 0 50% 50%;width:95px;height:70px;position:absolute;top:16px;left:26px;transform:rotate(180deg)}.axis i{background:var(--lime);border-radius:50%;width:7px;height:7px;position:absolute;top:57px;left:69px}.math-board>small{color:#aaa6bd;font-size:8px;position:absolute;bottom:25px;right:28px}.ticker{background:var(--lime);white-space:nowrap;padding:14px 0;font-weight:700;overflow:hidden;transform:rotate(-1deg)}.ticker div{word-spacing:30px;text-align:center;font-size:11px}.ticker span{color:var(--violet)}.topics,.latest{padding:120px 0}.section-heading{margin-bottom:45px}.section-heading p{color:var(--violet);margin:0 0 10px;font-size:9px;font-weight:700}.section-heading h2{letter-spacing:-1.5px;margin:0;font-size:clamp(30px,4vw,47px)}.section-heading>span{color:var(--muted);margin-top:12px;font-size:10px;display:block}.topic-grid{grid-template-columns:repeat(4,1fr);gap:13px;display:grid}.topic{border:1px solid var(--line);background:var(--white);border-radius:18px;min-height:260px;padding:23px;transition:transform .2s;position:relative;overflow:hidden}.topic:hover{transform:translateY(-5px)}.topic small{color:var(--muted);font:700 9px Arial}.topic>strong{text-align:left;color:var(--violet);direction:ltr;margin-top:42px;font:700 35px Georgia;display:block}.topic h3{margin:30px 0 8px;font-size:16px}.topic p{color:var(--muted);margin:0;font-size:9px}.topic>b{font-size:17px;position:absolute;bottom:20px;left:20px}.topic.amber>strong{color:#e89c23}.topic.cyan>strong{color:#1fa8b9}.topic.green>strong{color:#2b9b65}.featured{background:var(--violet);color:#fff;border-radius:27px;overflow:hidden;box-shadow:0 30px 65px #7356e833}.feature-label{border-bottom:1px solid #ffffff20;justify-content:space-between;padding:21px 32px;display:flex}.feature-label span{color:var(--lime);font-size:9px;font-weight:700}.feature-label small{color:#d7d1f7;font-size:8px}.feature-body{grid-template-columns:1fr .72fr;align-items:center;gap:75px;padding:55px;display:grid}.feature-body>div>p:first-child{color:var(--lime);font-size:9px;font-weight:700}.feature-body h2{letter-spacing:-1.5px;max-width:570px;margin:14px 0 15px;font-size:clamp(31px,4.2vw,49px);line-height:1.55}.feature-body>div>p:nth-of-type(2){color:#e0dcf5;max-width:540px;margin:0 0 25px;font-size:11px;line-height:2}.formula-card{background:var(--white);min-height:250px;color:var(--ink);border-radius:20px;padding:35px;position:relative;overflow:hidden;transform:rotate(-2deg)}.formula-card span{color:var(--violet);font-size:9px;font-weight:700}.formula-card strong{text-align:left;direction:ltr;margin-top:38px;font:700 31px Georgia;display:block}.formula-card i{border:35px solid var(--lime);border-radius:50%;width:180px;height:180px;position:absolute;bottom:-92px;left:-50px}.formula-card small{font-size:9px;position:absolute;bottom:30px;right:35px}.latest{padding-bottom:100px}.lesson-grid{grid-template-columns:repeat(3,1fr);gap:16px;display:grid}.lesson-grid article{border:1px solid var(--line);background:var(--white);border-radius:17px;padding:26px}.lesson-top{justify-content:space-between;display:flex}.lesson-top span{color:var(--violet);font:700 10px Arial}.lesson-top small{color:var(--violet);background:#eeeafc;border-radius:20px;padding:5px 8px;font-size:8px}.lesson-grid h3{min-height:62px;margin:24px 0 13px;font-size:17px;line-height:1.8}.lesson-grid>article>p{min-height:66px;color:var(--muted);margin:0;font-size:9px;line-height:2}.lesson-grid article>div:nth-of-type(2){gap:8px;margin:19px 0;display:flex}.lesson-grid article>div:nth-of-type(2) span{border:1px solid var(--line);color:var(--muted);border-radius:6px;padding:5px 8px;font-size:7px}.lesson-grid article>a{color:var(--violet);font-size:9px;font-weight:700}.method{border-top:1px solid var(--line);grid-template-columns:.65fr 1.35fr;gap:80px;padding:80px 0;display:grid}.method-title p{color:var(--violet);font-size:9px;font-weight:700}.method-title h2{font-size:35px;line-height:1.6}.method-steps{grid-template-columns:repeat(3,1fr);gap:13px;display:grid}.method-steps>div{border-top:3px solid var(--ink);background:#eeebe2;padding:26px 21px}.method-steps b{color:var(--violet);font:700 13px Arial}.method-steps h3{margin:31px 0 12px;font-size:14px}.method-steps p{color:var(--muted);margin:0;font-size:9px;line-height:2}.start{background:var(--ink);color:#fff;border-radius:24px;justify-content:space-between;align-items:center;gap:50px;margin-top:40px;padding:50px 55px;display:flex}.start span{color:var(--lime);font-size:9px;font-weight:700}.start h2{margin:12px 0;font-size:31px}.start p{color:#bdb9cb;max-width:650px;margin:0;font-size:10px;line-height:2}.light-button{background:var(--lime);color:var(--ink);border-radius:10px;flex:none;padding:14px 18px;font-size:9px;font-weight:700}.light-button b{margin-right:25px}.footer{justify-content:space-between;align-items:center;gap:30px;min-height:145px;display:flex}.footer>p{color:var(--muted);font-size:8px}.footer>div{gap:18px;font-size:8px;display:flex}.article-shell{width:min(980px,100% - 48px);margin:auto}.breadcrumbs{color:var(--muted);gap:8px;padding-top:35px;font-size:8px}.article-header{text-align:center;max-width:850px;margin:60px auto 70px}.article-meta{justify-content:center;gap:8px;display:flex}.article-meta span{color:var(--violet);background:#e8e3fa;border-radius:20px;padding:6px 9px;font-size:8px}.article-header h1{letter-spacing:-2px;margin:22px 0 18px;font-size:clamp(38px,5.4vw,61px);line-height:1.5}.article-header>p{max-width:700px;color:var(--muted);margin:0 auto;font-size:13px;line-height:2}.article-header>small{color:#9692a2;margin-top:25px;font-size:8px;display:block}.article-layout{grid-template-columns:190px minmax(0,650px);justify-content:center;align-items:start;gap:55px;display:grid}.article-layout aside{border:1px solid var(--line);background:var(--white);border-radius:14px;gap:13px;padding:20px;display:grid;position:sticky;top:20px}.article-layout aside strong{border-bottom:1px solid var(--line);padding-bottom:13px;font-size:9px}.article-layout aside a{color:var(--muted);font-size:8px;line-height:1.8}.article-content{color:#3b384b;font-size:13px;line-height:2.25}.article-content .lead{border-right:4px solid var(--violet);background:var(--white);color:var(--ink);border-radius:12px 0 0 12px;margin:0 0 50px;padding:24px;font-size:15px;font-weight:700}.article-content section{margin-bottom:55px;scroll-margin-top:25px}.section-number{color:var(--violet);font:700 10px Arial}.article-content h2{color:var(--ink);margin:8px 0 18px;font-size:25px}.article-content p{margin:0 0 16px}.article-content ul{background:#ece8fb;border-radius:14px;margin:22px 0;padding:20px 45px 20px 20px;list-style:none}.article-content li{position:relative}.article-content li:before{content:"+";color:var(--violet);font-weight:700;position:absolute;right:-24px}.takeaway{background:var(--ink);color:#fff;border-radius:17px;padding:27px}.takeaway span{color:var(--lime);font-size:8px;font-weight:700}.takeaway p{margin:10px 0 0}.source-note{background:#fff9e7;border:1px solid #decf9e;border-radius:13px;margin-top:16px;padding:20px}.source-note strong{font-size:9px}.source-note p{color:#6f6750;margin:7px 0 0;font-size:9px}.related{padding:100px 0}.related>div:last-child{grid-template-columns:repeat(3,1fr);gap:12px;display:grid}.related>div:last-child a{border:1px solid var(--line);background:var(--white);border-radius:15px;flex-direction:column;gap:10px;padding:22px;display:flex}.related span{color:var(--violet);font-size:8px}.related strong{font-size:11px;line-height:1.8}.related small{color:var(--muted);font-size:8px}.about{padding:100px 0 130px}.about h1{letter-spacing:-2px;max-width:950px;margin:25px 0;font-size:clamp(39px,5vw,59px);line-height:1.55}.about-lead{max-width:760px;color:var(--muted);font-size:13px;line-height:2.1}.about-grid{grid-template-columns:repeat(3,1fr);gap:14px;margin-top:65px;display:grid}.about-grid section{border:1px solid var(--line);background:var(--white);border-radius:17px;padding:28px}.about-grid span{color:var(--violet);font:700 10px Arial}.about-grid h2{margin:27px 0 12px;font-size:16px}.about-grid p{color:var(--muted);margin:0;font-size:9px;line-height:2}.contact{background:var(--ink);color:#fff;border-radius:17px;justify-content:space-between;align-items:center;margin-top:15px;padding:28px;display:flex}.contact>div{flex-direction:column;gap:8px;display:flex}.contact small{color:#aaa6b9;font-size:8px}.contact strong{font-size:12px}.contact>a{color:var(--lime);direction:ltr;font-size:10px}@media (max-width:850px){.shell{width:min(680px,100% - 32px)}.header nav{display:none}.hero{grid-template-columns:1fr;gap:55px}.math-board{min-height:470px}.topic-grid{grid-template-columns:repeat(2,1fr)}.feature-body,.lesson-grid{grid-template-columns:1fr}.lesson-grid h3,.lesson-grid>article>p{min-height:auto}.method,.article-layout{grid-template-columns:1fr}.article-layout aside{position:static}.related>div:last-child,.about-grid{grid-template-columns:1fr}}@media (max-width:520px){.header{height:74px}.header-cta,.logo small{display:none}.hero{padding:55px 0}.hero h1{letter-spacing:-2px;font-size:41px}.hero-proof{justify-content:space-between;gap:18px}.math-board{min-height:460px;padding:22px 18px}.equation{font-size:23px}.steps p{grid-template-columns:22px 1fr}.steps code{font-size:10px}.axis{opacity:.65}.topic-grid{grid-template-columns:1fr}.topic{min-height:220px}.feature-body{padding:35px 23px}.formula-card{min-height:220px}.method-steps{grid-template-columns:1fr}.start,.footer,.contact{flex-direction:column;align-items:flex-start}.footer{padding:40px 0}.article-header h1,.about h1{font-size:34px}.article-shell{width:calc(100% - 32px)}}@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}.topic{transition:none}}