:root{--bg:#f6f8fa;--card:#fff;--ink:#14213d;--muted:#5b6678;--line:#dde3ea;--brand:#0f766e;--brand-ink:#fff;--brand-soft:#e3f4f1;--accent:#b45309;--accent-soft:#fdf1dc;--ok:#15803d;--ok-soft:#e5f6ea;--bad:#b91c1c;--bad-soft:#fdeaea;--radius:14px;--shadow:0 1px 2px rgba(20,33,61,.06),0 6px 20px rgba(20,33,61,.06);--max:1040px}
@media (prefers-color-scheme:dark){:root{--bg:#0d1520;--card:#152233;--ink:#e8eef6;--muted:#9fb0c4;--line:#27384d;--brand:#2dd4bf;--brand-ink:#062a27;--brand-soft:#0f2f33;--accent:#fbbf24;--accent-soft:#33260c;--ok:#4ade80;--ok-soft:#10301c;--bad:#f87171;--bad-soft:#381717;--shadow:none}}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font:17px/1.6 system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;min-height:100vh;display:flex;flex-direction:column}
main{flex:1}
h1,h2,h3{line-height:1.2;margin:1.4em 0 .5em;letter-spacing:-.01em}
h1{font-size:clamp(1.7rem,6vw,2.5rem);margin-top:.8em}
h2{font-size:clamp(1.3rem,4.5vw,1.7rem)}
h3{font-size:1.15rem}
p{margin:.6em 0}
a{color:var(--brand)}
a:focus-visible,button:focus-visible,input:focus-visible,textarea:focus-visible,summary:focus-visible,.opt:focus-within{outline:3px solid var(--accent);outline-offset:2px}
.wrap{max-width:var(--max);margin-inline:auto;padding-inline:16px}
.wrap.narrow{max-width:560px}.wrap.wide{max-width:1200px}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
.skip{position:absolute;inset-inline-start:-999px;top:0;background:var(--brand);color:var(--brand-ink);padding:8px 12px;z-index:100}
.skip:focus{inset-inline-start:8px;top:8px}
.site-header{background:var(--card);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:20}
.hbar{display:flex;align-items:center;justify-content:space-between;gap:12px;min-height:58px;flex-wrap:wrap;padding-block:6px}
.brand{display:flex;align-items:center;gap:8px;text-decoration:none;color:var(--ink);font-weight:800;font-size:1.2rem}
.logo-mark{fill:var(--brand)}
.nav{display:flex;align-items:center;gap:4px 14px;flex-wrap:wrap;font-size:.95rem}
.nav a{text-decoration:none;color:var(--ink);padding:6px 4px}
.nav a.btn{color:var(--brand-ink)}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;background:var(--brand);color:var(--brand-ink);border:2px solid var(--brand);border-radius:999px;padding:12px 22px;font:inherit;font-weight:700;text-decoration:none;cursor:pointer;min-height:46px;text-align:center}
.btn:hover{filter:brightness(1.07)}
.btn[disabled]{opacity:.6;cursor:default}
.btn-small{padding:7px 16px;min-height:38px;font-size:.92rem}
.btn-big{padding:15px 28px;font-size:1.05rem}
.btn-ghost{background:transparent;color:var(--brand)}
.hero{background:linear-gradient(180deg,var(--brand-soft),var(--bg));padding-block:28px 24px}
.hero h1{margin-top:.2em;max-width:20ch}
.lead{font-size:1.15rem;color:var(--muted);max-width:60ch}
.cta-row{display:flex;gap:10px;flex-wrap:wrap;margin:16px 0}
.small{font-size:.88rem;color:var(--muted)}
.muted{color:var(--muted)}
.center{text-align:center}
.tiles{display:grid;gap:12px;grid-template-columns:1fr}
.tile{display:block;background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:16px 18px;text-decoration:none;color:var(--ink);box-shadow:var(--shadow);position:relative}
.tile:hover{border-color:var(--brand)}
.tile h3{margin:.3em 0}.tile p{color:var(--muted);margin:.2em 0 0;font-size:.95rem}
.tile-state{font-size:.78rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;color:var(--brand)}
.tile.soon .tile-state{color:var(--accent)}
.steps-list{list-style:none;counter-reset:s;padding:0;display:grid;gap:12px}
.steps-list li{counter-increment:s;background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:16px 18px 16px 62px;position:relative}
.steps-list li::before{content:counter(s);position:absolute;inset-inline-start:16px;top:14px;width:34px;height:34px;border-radius:50%;background:var(--brand);color:var(--brand-ink);display:grid;place-items:center;font-weight:800}
.steps-list h3{margin:0 0 .2em}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:18px;margin:14px 0;box-shadow:var(--shadow)}
.cards{display:grid;gap:12px;grid-template-columns:1fr}
.course-card{text-decoration:none;color:var(--ink);display:block}
.course-card h3{margin-top:0}
.price{font-size:1.1rem;margin:.2em 0}.price span{font-size:2.6rem;font-weight:800}
.price-card .card{max-width:560px}
.ticks{list-style:none;padding:0}.ticks li{padding-inline-start:28px;position:relative;margin:.35em 0}
.ticks li::before{content:"";position:absolute;inset-inline-start:2px;top:.55em;width:14px;height:8px;border-inline-start:3px solid var(--ok);border-bottom:3px solid var(--ok);transform:rotate(-45deg)}
.refund-note{background:var(--accent-soft);border-radius:10px;padding:10px 12px;font-size:.95rem}
.notice-box{background:var(--brand-soft);border:1px solid var(--line);border-radius:10px;padding:10px 14px;font-size:.88rem;color:var(--muted);margin:22px 0}
.datebox{background:var(--accent-soft);border-radius:10px;padding:10px 14px}
details{background:var(--card);border:1px solid var(--line);border-radius:10px;padding:10px 14px;margin:8px 0}
summary{cursor:pointer;font-weight:700}
.site-footer{border-top:1px solid var(--line);background:var(--card);padding-block:18px;margin-top:36px;font-size:.9rem;color:var(--muted)}
.foot-nav{display:flex;gap:6px 16px;flex-wrap:wrap}.foot-nav a{color:var(--muted)}
.cookie-note{position:fixed;inset-inline:10px;bottom:10px;background:var(--card);border:1px solid var(--line);box-shadow:0 8px 30px rgba(0,0,0,.2);border-radius:12px;padding:10px 14px;display:flex;gap:10px;align-items:center;z-index:50;font-size:.85rem}
.cookie-note[hidden]{display:none}.cookie-note p{margin:0}
label{display:block;font-weight:600;margin:12px 0 4px}
input[type=text],input[type=email],textarea{width:100%;font:inherit;padding:11px 12px;border:1.5px solid var(--line);border-radius:10px;background:var(--bg);color:var(--ink)}
.lead-form{display:flex;gap:8px;flex-wrap:wrap;align-items:flex-start}
.lead-form input{flex:1 1 220px;min-width:0}
.lead-form .form-msg,.lead-form .small{flex-basis:100%;margin:0}
.check{display:flex;gap:8px;align-items:flex-start;font-weight:400}.check input{margin-top:5px}
.form-msg{min-height:1.4em;color:var(--muted)}
.crumbs{font-size:.88rem;color:var(--muted);margin-top:14px}.crumbs a{color:var(--muted)}.crumbs .sep{margin-inline:6px}
.badge{display:inline-block;font-size:.72rem;font-weight:700;padding:2px 8px;border-radius:999px;background:var(--brand-soft);color:var(--brand);vertical-align:middle;white-space:nowrap}
.badge.pay{background:var(--accent-soft);color:var(--accent)}.badge.lock{background:var(--bad-soft);color:var(--bad)}.badge.done,.badge.ok{background:var(--ok-soft);color:var(--ok)}
.level{margin:20px 0}.unit-list{list-style:none;padding:0;margin:8px 0;display:grid;gap:8px}
.unit a,.unit>div{display:flex;align-items:center;gap:12px;background:var(--card);border:1px solid var(--line);border-radius:12px;padding:12px 14px;text-decoration:none;color:var(--ink);flex-wrap:wrap}
.unit a:hover{border-color:var(--brand)}.unit.locked>div,.unit.paywall a{opacity:.78}
.unit-no{flex:none;width:30px;height:30px;border-radius:50%;background:var(--brand-soft);color:var(--brand);display:grid;place-items:center;font-weight:800}
.unit-title{flex:1;min-width:0}.unit-title small{display:block;color:var(--muted)}
.why{flex-basis:100%;color:var(--muted)}
.mock-list{list-style:none;padding:0;display:grid;gap:8px}.mock-list li{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:12px 14px}
.progressbar{height:12px;background:var(--line);border-radius:99px;overflow:hidden;margin:10px 0}.progressbar span{display:block;height:100%;background:var(--brand);border-radius:99px}
.stats{display:flex;gap:12px;flex-wrap:wrap}.stat{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:12px 18px;min-width:130px}.stat strong{display:block;font-size:1.6rem}.stat span{color:var(--muted);font-size:.85rem}
.prose{max-width:760px}.prose img,.prose svg{max-width:100%;height:auto}
.prose h2{margin-top:1.6em;padding-top:.4em;border-top:1px solid var(--line)}
.prose table{border-collapse:collapse;width:100%;display:block;overflow-x:auto}.prose th,.prose td{border:1px solid var(--line);padding:6px 10px}
.prose blockquote{margin:1em 0;padding:.4em 1em;border-inline-start:4px solid var(--brand);background:var(--brand-soft);border-radius:6px}
.prose code{background:var(--brand-soft);padding:1px 5px;border-radius:5px}
.math-display{overflow-x:auto;overflow-y:hidden;padding:4px 0;max-width:100%}
.katex{font-size:1.06em}
.diagram{margin:1em 0;text-align:center}.diagram svg{max-width:100%;height:auto}.diagram figcaption{color:var(--muted);font-size:.88rem}
.toc{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:10px 16px;margin:14px 0;max-width:760px}.toc ol{margin:.3em 0;padding-inline-start:20px}
.lesson article{margin-top:14px}
.pager{display:flex;justify-content:space-between;gap:10px;margin:22px 0;flex-wrap:wrap}
.options{display:grid;gap:8px;margin:12px 0}
.opt{display:flex;gap:10px;align-items:flex-start;background:var(--card);border:1.5px solid var(--line);border-radius:12px;padding:10px 12px;cursor:pointer;font-weight:400;margin:0}
.opt:hover{border-color:var(--brand)}.opt input{margin-top:6px;flex:none}.opt:has(input:checked){border-color:var(--brand);background:var(--brand-soft)}
.opt-id{font-weight:800;color:var(--brand);flex:none;line-height:1.5}.opt-text>*{margin:0}.opt-text{line-height:1.5}.timer:empty{display:none}.opt-text{min-width:0;overflow-wrap:anywhere}
.answer-in{max-width:360px;margin:10px 0}
.feedback{margin-top:12px}.fb-head{font-weight:800;font-size:1.1rem}.fb-head.ok{color:var(--ok)}.fb-head.bad{color:var(--bad)}
.fb-expl,.fb-wrong,.fb-answer{background:var(--bg);border:1px solid var(--line);border-radius:10px;padding:10px 14px;margin:8px 0}
.fb-wrong{background:var(--accent-soft)}
.qblock{border:1px solid var(--line);border-radius:12px;padding:12px 16px;margin:14px 0;background:var(--card)}.qblock legend{font-weight:800;padding-inline:6px}
.sec-title small{font-weight:400;color:var(--muted)}
.timer{position:sticky;top:60px;z-index:10;background:var(--ink);color:var(--bg);font-weight:800;font-variant-numeric:tabular-nums;padding:8px 14px;border-radius:999px;display:inline-block;margin:8px 0}.timer.low{background:var(--bad);color:#fff}
.test-status p{margin:.4em 0}
.result-item{border-top:1px solid var(--line);padding-top:6px;margin-top:16px}
.topic-bars{list-style:none;padding:0;display:grid;gap:6px}.topic-bars li{display:grid;grid-template-columns:minmax(80px,1fr) 2fr 48px;gap:10px;align-items:center}
.topic-bars .bar{height:10px;background:var(--line);border-radius:99px;overflow:hidden;display:block}.topic-bars .bar i{display:block;height:100%;background:var(--brand)}
.toast{position:fixed;inset-inline:12px;bottom:70px;margin-inline:auto;max-width:460px;background:var(--ink);color:var(--bg);border-radius:14px;padding:12px 16px;display:flex;gap:10px;align-items:center;z-index:80;box-shadow:0 10px 30px rgba(0,0,0,.3);animation:pop .45s cubic-bezier(.2,1.3,.4,1)}
.toast.out{opacity:0;transform:translateY(10px);transition:all .5s}
.spark{width:14px;height:14px;border-radius:3px;background:var(--accent);transform:rotate(45deg);animation:spin 1s ease-out;flex:none}
@keyframes pop{from{transform:translateY(24px) scale(.9);opacity:0}to{transform:none;opacity:1}}
@keyframes spin{from{transform:rotate(-180deg) scale(.2)}to{transform:rotate(45deg) scale(1)}}
@media (prefers-reduced-motion:reduce){.toast,.spark{animation:none}}
.links-page{max-width:480px;padding-bottom:30px}
.link-btn{display:flex;justify-content:space-between;align-items:center;background:var(--brand);color:var(--brand-ink);text-decoration:none;font-weight:800;border-radius:16px;padding:16px 20px;margin:10px 0;font-size:1.05rem}
.link-btn small{font-weight:600;opacity:.85}.link-btn.alt{background:var(--card);color:var(--ink);border:1.5px solid var(--line)}
.table-wrap{overflow-x:auto}.report{border-collapse:collapse;width:100%;font-size:.9rem}.report th,.report td{border:1px solid var(--line);padding:6px 10px;text-align:end}.report th:first-child,.report td:first-child{text-align:start}
.gate{border-inline-start:6px solid var(--accent)}
.weak{padding-inline-start:20px}
.course-prog h3{margin-top:0}
@media (min-width:640px){.tiles{grid-template-columns:repeat(2,1fr)}.cards{grid-template-columns:repeat(2,1fr)}}
@media (min-width:900px){.tiles{grid-template-columns:repeat(3,1fr)}.hero{padding-block:56px 44px}body{font-size:18px}}
[hidden]{display:none!important}