:root{
  --bg:#f6f7f9;
  --card:#ffffff;
  --text:#1d2433;
  --muted:#6d7585;
  --line:#e6e8ee;
  --accent:#1f7a65;
  --accent2:#145a49;
  --soft:#eaf5f1;
}
*{box-sizing:border-box}
body{margin:0;font-family:Inter,system-ui,-apple-system,Segoe UI,Roboto,Arial,sans-serif;background:var(--bg);color:var(--text)}
.topbar{position:sticky;top:0;z-index:10;display:flex;align-items:center;justify-content:space-between;padding:16px 24px;background:rgba(255,255,255,.94);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.brand{font-weight:800;letter-spacing:.2px}
.lang-switcher{display:flex;gap:6px}
.lang-switcher button{border:1px solid var(--line);background:#fff;padding:7px 10px;border-radius:9px;cursor:pointer}
.lang-switcher button.active{background:var(--text);color:#fff;border-color:var(--text)}
.container{max-width:1100px;margin:0 auto;padding:28px 20px 60px}
.hero{display:grid;grid-template-columns:1.4fr .6fr;gap:28px;align-items:stretch;padding:34px 0 22px}
.hero>div:first-child{background:linear-gradient(135deg,#fff,#f3fbf8);border:1px solid var(--line);border-radius:24px;padding:36px}
.eyebrow{display:inline-block;font-size:12px;font-weight:800;letter-spacing:.12em;text-transform:uppercase;color:var(--accent);margin-bottom:10px}
h1{font-size:48px;line-height:1.03;margin:0 0 16px}
h2{margin-top:0;font-size:28px}
p{color:var(--muted);line-height:1.65}
.hero-actions{display:flex;gap:10px;margin-top:22px;flex-wrap:wrap}
button{font:inherit}
.primary,.secondary{padding:12px 18px;border-radius:12px;cursor:pointer;border:1px solid transparent;font-weight:700}
.primary{background:var(--accent);color:#fff}.primary:hover{background:var(--accent2)}
.secondary{background:#fff;border-color:var(--line);color:var(--text)}
.progress-card{background:var(--text);color:#fff;border-radius:24px;padding:28px;display:flex;flex-direction:column;justify-content:center}
.progress-title{color:#cfd5df;font-size:14px}.progress-number{font-size:48px;font-weight:800;margin:8px 0 12px}.progress-bar{height:10px;background:#394152;border-radius:99px;overflow:hidden}.progress-bar span{display:block;height:100%;width:0;background:#fff;border-radius:99px;transition:.3s}.small{font-size:13px;color:#cfd5df;margin-top:8px}
section{margin-top:34px}.grid{display:grid;grid-template-columns:repeat(4,1fr);gap:16px}.card{background:var(--card);border:1px solid var(--line);border-radius:18px;padding:20px;box-shadow:0 6px 24px rgba(35,44,59,.04)}
.card h3{margin:8px 0 10px;font-size:18px}.card p{font-size:14px;margin-bottom:18px}.badge{display:inline-flex;align-items:center;gap:6px;padding:6px 9px;background:var(--soft);color:var(--accent);border-radius:999px;font-size:12px;font-weight:700}.done{background:#eef8ee;color:#2b7a36}
.card button{width:100%}.panel{background:#fff;border:1px solid var(--line);border-radius:22px;padding:24px}.panel-head{display:flex;justify-content:space-between;gap:10px}.icon-btn{border:0;background:#f1f2f5;width:38px;height:38px;border-radius:10px;font-size:22px;cursor:pointer}.lesson-body{line-height:1.7}.lesson-body ul{padding-left:22px}.quiz{margin-top:24px;padding-top:20px;border-top:1px solid var(--line)}.quiz button{display:block;width:100%;text-align:left;margin:8px 0;padding:12px;border:1px solid var(--line);background:#fff;border-radius:10px;cursor:pointer}.quiz button:hover{border-color:var(--accent)}.quiz-result{margin-top:10px;font-weight:700}
.products .card{min-height:220px}.product-icon{font-size:28px}.ai-box{display:grid;grid-template-columns:.8fr 1.2fr;gap:18px;background:#0f1720;color:#fff;border-radius:24px;padding:28px}.ai-box p{color:#c6cbd3}.ai-demo{display:flex;flex-direction:column;gap:10px}.ai-demo input{padding:14px;border-radius:12px;border:1px solid #354253;background:#172230;color:#fff}.ai-answer{min-height:56px;padding:12px;border-radius:12px;background:#172230;color:#d7dce3;line-height:1.55}footer{text-align:center;padding:26px;color:#8a919d;font-size:13px}
@media(max-width:850px){.hero,.ai-box{grid-template-columns:1fr}.grid{grid-template-columns:repeat(2,1fr)}h1{font-size:38px}}
@media(max-width:560px){.topbar{padding:12px 14px}.brand{font-size:14px}.container{padding:18px 14px 44px}.hero>div:first-child,.progress-card{padding:22px;border-radius:18px}.grid{grid-template-columns:1fr}h1{font-size:33px}.panel{padding:18px}.ai-box{padding:20px}}
.example{padding:14px 16px;border:1px solid #ddd;border-radius:14px;margin:14px 0;background:#fafafa;line-height:1.55}
#lessonBody ol,#lessonBody ul{padding-left:22px;line-height:1.7}

.product-tools{display:flex;gap:12px;flex-wrap:wrap;align-items:center}.product-tools label{width:100%;font-weight:600}.product-tools input,.product-tools select{padding:12px;border:1px solid var(--line);border-radius:12px;font:inherit;max-width:100%}.product-tools input{flex:1;min-width:180px}.product-note{padding:16px;background:var(--soft);border-radius:12px}.product-step{border:0;margin:16px 0;padding:0}.product-step legend{font-weight:700}.product-step button:disabled{opacity:.75}.product-step .selected-correct{background:var(--soft);border-color:var(--accent)}#productPanel{scroll-margin-top:90px}button:focus-visible,input:focus-visible,select:focus-visible{outline:3px solid #319b86;outline-offset:3px}@media(max-width:600px){.product-tools>*{width:100%}.topbar{padding:12px}.brand{font-size:14px}}

[hidden]{display:none!important}.auth-gate{max-width:620px}.auth-gate h1{font-size:32px}.auth-gate form{display:grid;gap:12px;margin-top:24px}.auth-gate label{display:block;font-weight:600}.auth-gate input{display:block;width:100%;padding:13px;border:1px solid var(--line);border-radius:10px;font:inherit;margin-top:6px}.auth-gate button{margin-top:8px}.account-bar{display:flex;align-items:center;justify-content:space-between;padding-bottom:0}.auth-gate #authError{color:#a52828}button:disabled{opacity:.6;cursor:wait}a{color:var(--accent)}