:root{--bg:#07080c;--surface:#0d1017;--surface-2:#111620;--text:#f5f7fb;--muted:#98a2b3;--soft:#cbd1dc;--border:rgba(255,255,255,.09);--border-strong:rgba(255,255,255,.16);--accent:#8b7cff;--accent-2:#62d9ff;--good:#6ee7b7;--shadow:0 30px 80px rgba(0,0,0,.34);--nav:rgba(7,8,12,.72)}
[data-theme="light"]{--bg:#f6f7fa;--surface:#fff;--surface-2:#edf0f5;--text:#10131a;--muted:#626b7a;--soft:#343b48;--border:rgba(16,19,26,.09);--border-strong:rgba(16,19,26,.16);--nav:rgba(246,247,250,.78);--shadow:0 24px 65px rgba(20,28,45,.12)}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--bg);color:var(--text);font-family:Inter,ui-sans-serif,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;overflow-x:hidden;line-height:1.5}a{color:inherit;text-decoration:none}button,input,textarea{font:inherit}.bg{position:fixed;inset:0;z-index:-2;background:radial-gradient(circle at 74% 5%,rgba(98,217,255,.09),transparent 24%),radial-gradient(circle at 22% 28%,rgba(139,124,255,.11),transparent 28%),linear-gradient(rgba(255,255,255,.018) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.018) 1px,transparent 1px),var(--bg);background-size:auto,auto,64px 64px,64px 64px,auto}.nav{height:76px;max-width:1240px;margin:auto;padding:0 24px;display:flex;align-items:center;justify-content:space-between;gap:24px;position:relative;z-index:20}.logo{display:inline-flex;align-items:center;gap:10px;font-size:19px;font-weight:750;letter-spacing:-.025em}.logo-mark{width:31px;height:31px;display:grid;place-items:center;border:1px solid var(--border-strong);border-radius:9px;background:linear-gradient(145deg,rgba(139,124,255,.22),rgba(98,217,255,.08));font-family:Georgia,serif;font-size:17px}.links{display:flex;align-items:center;gap:6px}.links a,.theme-toggle{padding:9px 12px;border-radius:9px;color:var(--muted);font-size:14px;font-weight:600;border:0;background:transparent;cursor:pointer;transition:.2s}.links a:hover,.links a.active,.theme-toggle:hover{color:var(--text);background:rgba(255,255,255,.055)}.links .nav-cta{color:#080a10;background:var(--text);padding:10px 15px;margin-left:5px}.links .nav-cta:hover{color:#080a10;background:#fff;transform:translateY(-1px)}.menu-toggle{display:none;color:var(--text);background:transparent;border:1px solid var(--border);border-radius:9px;padding:8px 12px}.container{width:min(1160px,calc(100% - 40px));margin:auto;padding:92px 0}.hero{min-height:calc(100vh - 76px);display:grid;grid-template-columns:1.02fr .98fr;align-items:center;gap:68px;padding-top:74px;padding-bottom:90px}.eyebrow{display:inline-flex;align-items:center;gap:10px;padding:7px 11px;border:1px solid var(--border);border-radius:999px;background:rgba(255,255,255,.025);font-size:13px;font-weight:600;color:var(--soft)}.status-dot{width:7px;height:7px;border-radius:50%;background:var(--good);box-shadow:0 0 16px var(--good)}.h1{font-size:clamp(50px,6.2vw,82px);line-height:1.01;letter-spacing:-.067em;margin:24px 0;color:var(--text);font-weight:730}.grad{background:linear-gradient(105deg,#fff 5%,#bcb4ff 48%,#70dfff 95%);-webkit-background-clip:text;background-clip:text;color:transparent}.lead{font-size:clamp(18px,1.7vw,21px);line-height:1.68;color:var(--muted);max-width:700px}.lead.small{font-size:18px}.cta{display:flex;gap:12px;flex-wrap:wrap;margin-top:31px}.btn{display:inline-flex;align-items:center;justify-content:center;gap:15px;min-height:50px;padding:0 19px;border-radius:11px;background:var(--text);color:#080a10;font-size:14px;font-weight:750;box-shadow:0 8px 28px rgba(0,0,0,.18);transition:.22s}.btn:hover{transform:translateY(-2px);box-shadow:0 12px 34px rgba(0,0,0,.25)}.btn.secondary{background:rgba(255,255,255,.035);color:var(--text);border:1px solid var(--border)}.hero-proof{display:flex;gap:0;margin-top:52px}.hero-proof div{display:flex;flex-direction:column;padding:0 28px;border-left:1px solid var(--border)}.hero-proof div:first-child{padding-left:0;border-left:0}.hero-proof strong{font-size:13px}.hero-proof span{font-size:12px;color:var(--muted);margin-top:4px}.visual{position:relative;height:550px;border:1px solid var(--border);border-radius:24px;background:linear-gradient(145deg,rgba(255,255,255,.06),rgba(255,255,255,.015));box-shadow:var(--shadow);overflow:hidden}.visual:before{content:"";position:absolute;width:280px;height:280px;right:-70px;top:-80px;border-radius:50%;background:rgba(98,217,255,.12);filter:blur(65px)}.visual-grid{position:absolute;inset:0;background-image:linear-gradient(rgba(255,255,255,.035) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.035) 1px,transparent 1px);background-size:38px 38px;mask-image:linear-gradient(to bottom,#000,transparent 88%)}.visual-topbar{position:relative;z-index:2;height:58px;padding:0 19px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--border);font-size:12px;font-weight:650;color:var(--soft)}.visual-status{color:var(--good)}.equation-stage{position:relative;margin:36px 28px 0;height:315px;border:1px solid var(--border);border-radius:18px;background:rgba(5,7,12,.42);padding:28px;overflow:hidden}.equation-label{font-size:12px;color:var(--muted)}.equation{font-family:Georgia,"Times New Roman",serif;font-size:clamp(31px,4vw,46px);margin-top:42px;letter-spacing:-.03em}.equation-result{font-family:Georgia,"Times New Roman",serif;font-size:24px;color:#a9e9ff;margin-top:18px;opacity:0;transform:translateY(8px);animation:solve 6s ease-in-out infinite}.curve{position:absolute;right:20px;bottom:13px;width:170px;height:100px;border-left:1px solid rgba(255,255,255,.15);border-bottom:1px solid rgba(255,255,255,.15)}.curve span{display:block;position:absolute;inset:8px 10px 10px 5px;border-top:2px solid var(--accent-2);border-radius:50% 50% 0 0;transform:skewY(-25deg) rotate(-8deg);filter:drop-shadow(0 0 8px rgba(98,217,255,.5))}.glass{position:absolute;left:28px;right:28px;bottom:25px;padding:17px 18px;border-radius:15px;border:1px solid var(--border);background:rgba(13,16,23,.72);backdrop-filter:blur(18px)}.glass-heading{display:flex;justify-content:space-between;font-size:12px}.glass p{margin:9px 0 0;font-size:12px;color:var(--muted)}.progress{height:5px;margin-top:12px;border-radius:999px;background:rgba(255,255,255,.08);overflow:hidden}.progress span{display:block;height:100%;border-radius:inherit;background:linear-gradient(90deg,var(--accent),var(--accent-2))}.trust-strip{max-width:1160px;margin:auto;padding:25px 0;border-top:1px solid var(--border);border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:center;gap:24px;color:var(--muted);font-size:12px;font-weight:650;letter-spacing:.02em}.trust-strip i{width:3px;height:3px;background:var(--border-strong);border-radius:50%}.section-heading{display:grid;grid-template-columns:1fr .65fr;gap:60px;align-items:end;margin-bottom:42px}.section-heading p{margin:0;color:var(--muted);line-height:1.7}.kicker{display:block;color:#8fdfff;font-size:11px;font-weight:800;letter-spacing:.18em;margin-bottom:13px}.section-title{font-size:clamp(36px,4.5vw,58px);line-height:1.08;letter-spacing:-.052em;margin:0}.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}.card{min-height:310px;padding:25px;border-radius:18px;background:rgba(255,255,255,.025);border:1px solid var(--border);position:relative;display:flex;flex-direction:column;transition:.25s}.card:hover{transform:translateY(-5px);background:rgba(255,255,255,.045);border-color:var(--border-strong)}.card.featured{background:linear-gradient(145deg,rgba(139,124,255,.10),rgba(255,255,255,.025))}.card-index{color:var(--muted);font-family:Georgia,serif;font-size:14px}.card-tag{position:absolute;right:20px;top:20px;padding:5px 8px;border-radius:999px;background:rgba(110,231,183,.09);color:var(--good);font-size:10px;font-weight:750}.muted-tag{background:rgba(255,255,255,.05);color:var(--muted)}.card h3{font-size:24px;letter-spacing:-.035em;margin:70px 0 12px}.card p,.card li{color:var(--muted);line-height:1.65;margin:0}.card-link{margin-top:auto;padding-top:30px;font-size:13px;font-weight:700}.split-section{display:grid;grid-template-columns:1fr .85fr;gap:110px;align-items:start;border-top:1px solid var(--border)}.concept-panel .section-title{font-size:clamp(38px,4vw,53px)}.text-link{display:inline-block;margin-top:22px;font-size:14px;font-weight:700;color:var(--soft)}.method-list{border-top:1px solid var(--border)}.method{display:grid;grid-template-columns:55px 1fr;gap:12px;padding:27px 0;border-bottom:1px solid var(--border)}.method>span{font-family:Georgia,serif;color:var(--muted)}.method h3{margin:0 0 7px;font-size:17px}.method p{margin:0;color:var(--muted);font-size:14px;line-height:1.65}.final-cta{margin-bottom:70px;padding:54px;border:1px solid var(--border);border-radius:22px;background:linear-gradient(135deg,rgba(139,124,255,.09),rgba(98,217,255,.04));display:flex;align-items:center;justify-content:space-between;gap:30px}.final-cta h2{font-size:clamp(30px,4vw,48px);letter-spacing:-.045em;margin:0}.footer{max-width:1160px;margin:auto;padding:38px 0 48px;border-top:1px solid var(--border);display:flex;align-items:end;justify-content:space-between;color:var(--muted);font-size:12px}.footer p{margin:10px 0 0}.reveal{opacity:0;transform:translateY(20px);transition:opacity .7s ease,transform .7s ease}.reveal.show{opacity:1;transform:none}.search{width:100%;padding:15px 17px;border-radius:11px;border:1px solid var(--border);background:var(--surface);color:var(--text);font-size:15px;outline:none}.breadcrumb{color:var(--muted);font-size:13px;font-weight:600;margin-bottom:22px}.breadcrumb a:hover{color:var(--text)}.pill{display:inline-block;padding:6px 9px;border:1px solid var(--border);border-radius:999px;color:var(--muted);font-size:12px;margin:3px}.topic-list{display:grid;gap:9px}.lesson-row{display:flex;align-items:center;justify-content:space-between;gap:15px;padding:17px 19px;border-radius:13px;background:rgba(255,255,255,.025);border:1px solid var(--border);transition:.2s}.lesson-row:hover{background:rgba(255,255,255,.05);transform:translateX(3px)}.code{font-weight:750;color:#8fdfff}.orb,.formula{display:none}
/* Interactive lessons */.lesson-hero{padding-top:44px}.lesson-meta{display:flex;gap:8px;flex-wrap:wrap;margin:20px 0}.lesson-shell{display:grid;grid-template-columns:1.1fr .9fr;gap:18px;align-items:start}.video-stage{min-height:420px;border-radius:20px;border:1px solid var(--border);background:linear-gradient(145deg,rgba(255,255,255,.04),rgba(139,124,255,.06));box-shadow:var(--shadow);position:relative;overflow:hidden;padding:26px}.stage-title{position:absolute;top:22px;left:24px;font-weight:750;color:#8fdfff;z-index:3}.math-board{position:absolute;inset:76px 24px 96px;border-radius:16px;background:rgba(0,0,0,.15);border:1px solid var(--border);display:flex;align-items:center;justify-content:center;flex-direction:column;text-align:center;padding:20px}.proof-line{opacity:0;transform:translateY(14px);transition:.5s;font-size:clamp(22px,3vw,36px);font-weight:700;margin:8px}.proof-line.active{opacity:1;transform:none}.highlight-blue{color:#8fdfff}.highlight-green{color:#8cebc5}.highlight-orange{color:#ffc187}.highlight-purple{color:#bcb4ff}.video-controls{position:absolute;bottom:22px;left:24px;right:24px;display:flex;gap:10px;flex-wrap:wrap;align-items:center}.mini-progress{height:6px;flex:1;min-width:150px;border-radius:999px;background:rgba(255,255,255,.08);overflow:hidden}.mini-progress span{display:block;height:100%;width:0;background:linear-gradient(90deg,var(--accent),var(--accent-2));transition:.4s}.lesson-panel{display:grid;gap:12px}.step-card{padding:20px;border-radius:16px;border:1px solid var(--border);background:rgba(255,255,255,.025)}.step-card h3{margin:0 0 8px}.example-question{font-size:21px;line-height:1.6}.quiz-option{display:block;width:100%;text-align:left;margin:9px 0;padding:13px 15px;border-radius:11px;border:1px solid var(--border);background:rgba(255,255,255,.025);color:var(--text);cursor:pointer;font-weight:650}.quiz-option:hover{background:rgba(255,255,255,.06)}.quiz-feedback{margin-top:10px;font-weight:700;min-height:24px}.timeline{display:grid;gap:12px;margin-top:18px}.timeline-step{display:flex;gap:12px;align-items:flex-start}.timeline-dot{width:27px;height:27px;border-radius:50%;background:linear-gradient(135deg,var(--accent-2),var(--accent));display:grid;place-items:center;font-weight:800;flex:0 0 auto}.formula-rain{position:absolute;inset:0;pointer-events:none;opacity:.16}.formula-rain span{position:absolute;font-weight:700}.script-box{white-space:pre-wrap;line-height:1.7;color:var(--muted)}.lesson-video{display:flex;justify-content:center;margin:40px auto}.lesson-video video{width:min(420px,90vw);aspect-ratio:9/16;object-fit:cover;border-radius:20px;box-shadow:var(--shadow);border:1px solid var(--border);background:#000}
@keyframes solve{0%,20%{opacity:0;transform:translateY(8px)}35%,82%{opacity:1;transform:none}100%{opacity:0;transform:translateY(-5px)}}
@media(max-width:900px){.nav{height:68px}.menu-toggle{display:block}.links{display:none;position:absolute;top:62px;left:20px;right:20px;padding:12px;background:var(--surface);border:1px solid var(--border);border-radius:14px;box-shadow:var(--shadow);flex-direction:column;align-items:stretch}.links.open{display:flex}.links a,.theme-toggle{text-align:left}.links .nav-cta{margin:4px 0 0;text-align:center}.hero{grid-template-columns:1fr;min-height:auto;gap:50px;padding-top:70px}.visual{height:500px}.section-heading,.split-section{grid-template-columns:1fr;gap:30px}.grid{grid-template-columns:1fr}.card{min-height:270px}.trust-strip{width:calc(100% - 40px);flex-wrap:wrap}.hero-proof{flex-wrap:wrap;gap:18px}.hero-proof div{padding:0 18px}.lesson-shell{grid-template-columns:1fr}.final-cta{padding:36px;align-items:flex-start;flex-direction:column}.footer{width:calc(100% - 40px)}}
@media(max-width:560px){.container{width:min(100% - 30px,1160px);padding:70px 0}.h1{font-size:47px}.hero-proof{display:none}.visual{height:440px}.equation-stage{margin:22px 15px 0;height:270px;padding:20px}.equation{margin-top:36px}.glass{left:15px;right:15px;bottom:15px}.trust-strip{justify-content:flex-start;gap:12px}.trust-strip i{display:none}.footer{align-items:flex-start;flex-direction:column;gap:22px}.lesson-row{align-items:flex-start;flex-direction:column}}