:root{
  --ink:#0f172a;--ink-soft:#475569;--muted:#94a3b8;--line:#e2e8f0;
  --bg:#f8fafc;--card:#fff;--accent:#4f46e5;--accent-dark:#4338ca;--accent-soft:#eef2ff;
  --green:#059669;--green-soft:#ecfdf5;
}
*{box-sizing:border-box;margin:0;padding:0}
body{font-family:Inter,system-ui,sans-serif;color:var(--ink);background:var(--bg);line-height:1.5}
.container{max-width:1200px;margin:0 auto;padding:0 24px}
.nav{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.9);backdrop-filter:blur(12px);border-bottom:1px solid var(--line)}
.nav-inner{display:flex;justify-content:space-between;align-items:center;height:64px}
.brand{font-weight:800;font-size:1.15rem;text-decoration:none;color:var(--ink)}
.brand span{color:var(--accent)}
.demo-badge{font-size:.65rem;font-weight:800;letter-spacing:.08em;background:var(--accent);color:#fff;padding:3px 7px;border-radius:6px;vertical-align:middle;margin-left:6px}
.nav-links{display:flex;gap:18px;align-items:center}
.nav-links a{color:var(--ink-soft);text-decoration:none;font-weight:500;font-size:.9rem}
.nav-note{font-size:.75rem;color:var(--muted);border:1px dashed var(--line);padding:4px 8px;border-radius:999px}
.hero{padding:64px 0 48px;text-align:center}
.hero h1{font-size:clamp(2.1rem,5vw,3.5rem);font-weight:800;letter-spacing:-.03em;line-height:1.1}
.gradient{background:linear-gradient(90deg,var(--accent),#9333ea);-webkit-background-clip:text;background-clip:text;color:transparent}
.hero-sub{margin-top:16px;color:var(--ink-soft);font-size:1.1rem;max-width:640px;margin-left:auto;margin-right:auto}
.hero-pills{margin-top:22px;display:flex;gap:8px;justify-content:center;flex-wrap:wrap}
.hero-cta{margin-top:26px}
.pill{font-size:.82rem;font-weight:600;color:var(--green);background:var(--green-soft);padding:6px 12px;border-radius:999px}
.tool-section{display:grid;grid-template-columns:minmax(0,440px) minmax(0,1fr);gap:28px;padding-bottom:48px;align-items:start}
.card{background:var(--card);border:1px solid var(--line);border-radius:16px;padding:24px;box-shadow:0 1px 3px rgba(15,23,42,.06)}
.card-title{font-size:.8rem;font-weight:700;text-transform:uppercase;letter-spacing:.08em;color:var(--accent)}
.count{color:var(--muted);font-weight:600;text-transform:none;letter-spacing:0}
.tabs{display:flex;gap:6px;margin-bottom:16px}
.tab{flex:1;border:1.5px solid var(--line);background:#fff;border-radius:10px;padding:9px 6px;font-family:inherit;font-weight:600;font-size:.85rem;cursor:pointer;color:var(--ink-soft)}
.tab.active{border-color:var(--accent);color:var(--accent);background:var(--accent-soft)}
.tab-panel textarea,.tab-panel input[type="url"]{width:100%;padding:11px 12px;border:1px solid var(--line);border-radius:10px;font-family:inherit;font-size:.92rem}
.tab-panel textarea:focus,.tab-panel input:focus{outline:none;border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-soft)}
.hint{font-size:.78rem;color:var(--muted);margin-top:8px}
.dropzone{border:2px dashed var(--muted);border-radius:12px;padding:28px 16px;text-align:center;cursor:pointer;background:#fff;transition:.15s}
.dropzone:hover,.dropzone.dragover{border-color:var(--accent);background:var(--accent-soft)}
.dz-icon{font-size:1.6rem}
.dz-main{font-size:.92rem}
.dz-sub{font-size:.78rem;color:var(--muted);margin-top:4px}
.gen-row{display:flex;gap:10px;align-items:end;margin-top:18px;flex-wrap:wrap}
.output-tabs{display:flex;gap:6px;margin-bottom:14px}
.out-tab{flex:1;border:1.5px solid var(--line);background:#fff;border-radius:10px;padding:10px;font-family:inherit;font-weight:700;font-size:.85rem;cursor:pointer;color:var(--ink-soft)}
.out-tab.active{border-color:var(--accent);color:var(--accent);background:var(--accent-soft)}
.toolbar-label{font-size:.78rem;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:var(--accent)}
.field.inline span{display:block;font-size:.75rem;font-weight:600;color:var(--ink-soft);margin-bottom:4px}
.field.inline select{padding:9px 10px;border:1px solid var(--line);border-radius:8px;font-family:inherit;font-size:.9rem}
.demo-note{font-size:.72rem;color:var(--muted);margin-top:8px}
.btn{border:none;cursor:pointer;font-family:inherit;font-weight:600;border-radius:10px;padding:10px 16px;transition:.15s}
.btn-primary{background:var(--accent);color:#fff}
.btn-primary:hover{background:var(--accent-dark)}
.btn-secondary{background:var(--accent-soft);color:var(--accent)}
.btn-ghost{background:transparent;color:var(--ink-soft)}
.btn-ghost:hover{background:var(--line)}
.btn-lg{padding:12px 22px}
.btn-sm{padding:7px 12px;font-size:.85rem}
.deck-col .toolbar{display:flex;justify-content:space-between;align-items:center;margin-bottom:12px}
.toolbar-actions{display:flex;gap:6px}
.deck{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:12px}
.empty-state{text-align:center;color:var(--ink-soft);padding:36px 20px}
.flash{border:1px solid var(--line);border-radius:14px;background:#fff;overflow:hidden;cursor:pointer;transition:.12s}
.flash:hover{transform:translateY(-2px);box-shadow:0 6px 18px rgba(15,23,42,.08)}
.flash-inner{padding:16px;min-height:132px;display:flex;flex-direction:column}
.flash-q{font-weight:600;font-size:.92rem}
.flash-a{margin-top:10px;padding-top:10px;border-top:1px dashed var(--line);font-size:.88rem;color:var(--ink-soft)}
.flash-a.hidden{visibility:hidden}
.flash-meta{margin-top:auto;padding-top:10px;font-size:.68rem;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.overlay{position:fixed;inset:0;background:rgba(15,23,42,.55);backdrop-filter:blur(4px);display:flex;align-items:center;justify-content:center;padding:20px;z-index:100}
.overlay[hidden]{display:none !important}
.overlay-card{width:min(640px,100%)}
.overlay-head{display:flex;justify-content:space-between;align-items:center;margin-bottom:16px}
.progress{font-size:.85rem;font-weight:600;color:var(--muted)}
.study-card{background:var(--accent-soft);border-radius:14px;padding:28px;min-height:180px;display:flex;flex-direction:column;justify-content:center}
.study-q{font-size:1.15rem;font-weight:700}
.study-a{margin-top:16px;padding-top:16px;border-top:1px solid #c7d2fe;font-size:1rem;color:var(--ink-soft)}
.study-a.hidden{visibility:hidden}
.study-actions{margin-top:16px;display:flex;gap:8px;justify-content:center;flex-wrap:wrap}
.grade-row{display:flex;gap:8px}
.features{padding:28px 24px 40px}
.features h2,.faq h2{font-size:1.6rem;font-weight:800;text-align:center;margin-bottom:28px;letter-spacing:-.02em}
.feature-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:16px}
.feature{background:#fff;border:1px solid var(--line);border-radius:14px;padding:20px}
.feature h3{font-size:.95rem;margin-bottom:6px}
.feature p{font-size:.88rem;color:var(--ink-soft)}
.faq{padding-bottom:72px;max-width:720px}
.faq details{background:#fff;border:1px solid var(--line);border-radius:12px;margin-bottom:8px;padding:14px 18px}
.faq summary{font-weight:600;cursor:pointer}
.faq p{margin-top:8px;color:var(--ink-soft);font-size:.9rem}
.faq code{background:var(--bg);padding:2px 6px;border-radius:6px;font-size:.85em}
.footer{border-top:1px solid var(--line);padding:22px 0;color:var(--muted);font-size:.82rem;text-align:center}
.quiz-list{display:flex;flex-direction:column;gap:12px}
.quiz-q{border:1px solid var(--line);border-radius:14px;background:#fff;padding:18px}
.quiz-q-head{font-weight:600;font-size:.95rem;margin-bottom:12px}
.quiz-opts{display:flex;flex-direction:column;gap:8px}
.quiz-opt{border:1.5px solid var(--line);border-radius:10px;padding:10px 12px;font-size:.9rem;cursor:pointer;transition:.12s;background:#fff;text-align:left;width:100%;font-family:inherit}
.quiz-opt:hover{border-color:var(--accent);background:var(--accent-soft)}
.quiz-opt.correct{border-color:var(--green);background:var(--green-soft);color:var(--green)}
.quiz-opt.wrong{border-color:#fecaca;background:#fef2f2;color:#dc2626}
.quiz-opt:disabled{cursor:default}
.quiz-explain{margin-top:10px;font-size:.82rem;color:var(--ink-soft);background:var(--bg);padding:10px 12px;border-radius:8px}
.score-bar{margin-top:14px;text-align:center;font-weight:700;padding:14px;background:var(--green-soft);color:var(--green);border-radius:12px}
.quiz-options{display:flex;flex-direction:column;gap:8px;margin-top:14px}
.quiz-feedback{margin-top:14px;padding:12px;border-radius:10px;font-size:.9rem}
.quiz-feedback.ok{background:var(--green-soft);color:var(--green)}
.quiz-feedback.bad{background:#fef2f2;color:#dc2626}
.pricing{padding:24px 24px 48px;text-align:center}
.pricing-sub{color:var(--ink-soft);margin:8px 0 24px}
.pricing-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:16px;max-width:960px;margin:0 auto;text-align:left}
.price-card{background:#fff;border:1px solid var(--line);border-radius:16px;padding:24px;position:relative}
.price-card.featured{border-color:var(--accent);box-shadow:0 8px 24px rgba(79,70,229,.12);transform:translateY(-2px)}
.popular{position:absolute;top:-12px;left:50%;transform:translateX(-50%);background:var(--accent);color:#fff;font-size:.7rem;font-weight:800;letter-spacing:.08em;padding:4px 10px;border-radius:999px}
.price-card h3{font-size:1.05rem;margin-bottom:6px}
.price{font-size:2rem;font-weight:800}
.price span{font-size:.9rem;font-weight:600;color:var(--muted)}
.save{margin-left:8px;background:var(--green-soft);color:var(--green);padding:3px 8px;border-radius:999px;font-size:.75rem}
.price-card ul{list-style:none;margin:14px 0 18px}
.price-card li{font-size:.88rem;padding:4px 0;color:var(--ink-soft)}
.price-note{font-size:.68rem;color:var(--muted);margin-top:8px;text-align:center}
.btn-block{width:100%;text-align:center;display:inline-block;text-decoration:none}
.footer a{color:var(--muted);text-decoration:none}
.footer a:hover{color:var(--ink)}
@media(max-width:900px){.tool-section{grid-template-columns:1fr}.hero{padding:40px 0 32px}}