:root{--bg:#f7f8fa;--card:#fff;--ink:#111827;--muted:#6b7280;--line:#e5e7eb;--accent:#635bff;--accent2:#7c3aed;--good:#16a34a;--bad:#dc2626;--shadow:0 12px 35px rgba(17,24,39,.08)}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font-family:Inter,ui-sans-serif,system-ui,-apple-system,"Segoe UI",sans-serif}button{font:inherit;border:0;cursor:pointer;-webkit-tap-highlight-color:transparent}#app{max-width:560px;margin:auto;min-height:100vh;padding:20px 18px 92px}.screen{display:none;min-height:calc(100vh - 112px);flex-direction:column}.screen.active{display:flex}.hero-head{display:flex;align-items:center;gap:12px;padding:8px 0 20px}.brand-mark{width:42px;height:42px;border-radius:14px;background:var(--ink);color:#fff;display:grid;place-items:center;font-size:22px}.eyebrow{font-size:11px;font-weight:900;letter-spacing:.14em;color:var(--accent)}.hero-title{font-size:15px;font-weight:800;margin-top:2px}.icon-btn{width:42px;height:42px;border-radius:14px;background:#fff;color:var(--ink);box-shadow:0 4px 16px rgba(17,24,39,.07);font-size:20px;margin-left:auto}.profile-card{background:linear-gradient(135deg,#171827,#252448);color:#fff;border-radius:24px;padding:20px;box-shadow:var(--shadow);margin-bottom:14px}.muted{font-size:13px;color:#d1d5db}.profile-card h2{margin:8px 0 12px;font-size:27px}.profile-card h2 small{font-size:12px;color:#c7c9d5;font-weight:600}.xp-line{display:flex;justify-content:space-between;font-size:12px;color:#d1d5db;margin-bottom:7px}.xp{height:7px;background:#ffffff20;border-radius:9px;overflow:hidden}.xp i{display:block;height:100%;width:0;background:#fff;border-radius:9px;transition:.35s}.primary{background:var(--ink);color:#fff;border-radius:18px;padding:16px 18px;font-weight:800;box-shadow:0 10px 22px rgba(17,24,39,.12)}.big-btn{display:flex;align-items:center;gap:14px;text-align:left;margin-bottom:25px}.big-btn>span:first-child{font-size:21px;width:35px}.big-btn span:nth-child(2){display:flex;flex-direction:column;flex:1}.big-btn small{font-size:11px;color:#bfc3cc;font-weight:600;margin-top:3px}.big-btn strong{font-size:20px}.section-title{display:flex;justify-content:space-between;align-items:center;margin:7px 0 12px}.text-btn{background:none;color:var(--accent);font-size:12px;font-weight:800}.challenge-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:10px;margin-bottom:23px}.challenge{padding:15px;text-align:left;border-radius:19px;background:#fff;border:1px solid var(--line);box-shadow:0 5px 18px rgba(17,24,39,.04);display:flex;flex-direction:column;gap:4px}.challenge span{font-size:20px}.challenge b{font-size:15px}.challenge small{font-size:10px;color:var(--muted)}.challenge:active,.category-chip:active,.answer:active{transform:scale(.98)}.category-scroll{display:flex;gap:9px;overflow:auto;padding-bottom:10px;scrollbar-width:none}.category-scroll::-webkit-scrollbar{display:none}.category-chip{min-width:105px;background:#fff;border:1px solid var(--line);border-radius:17px;padding:13px;text-align:left}.category-chip span{font-size:18px}.category-chip b{display:block;font-size:12px;margin-top:5px}.category-chip small{color:var(--muted);font-size:10px}.bottom-nav{position:fixed;bottom:0;left:50%;transform:translateX(-50%);width:min(560px,100%);padding:10px 14px calc(10px + env(safe-area-inset-bottom));background:rgba(255,255,255,.94);backdrop-filter:blur(12px);display:grid;grid-template-columns:repeat(4,1fr);border-top:1px solid var(--line);z-index:5}.bottom-nav button{background:none;color:#9ca3af;display:flex;flex-direction:column;align-items:center;gap:3px;font-size:18px}.bottom-nav button.active{color:var(--accent)}.bottom-nav small{font-size:10px;font-weight:800}.quiz-head{display:flex;align-items:center;gap:12px;padding:5px 0 15px}.quiz-head .icon-btn{margin:0}.quiz-head>div:nth-child(2){display:flex;flex-direction:column;flex:1}.quiz-head small{font-size:10px;color:var(--muted);margin-top:2px}.timer{width:44px;height:44px;border-radius:50%;background:#fff;border:2px solid var(--ink);display:grid;place-items:center;font-weight:900}.progress-label{display:flex;justify-content:space-between;font-size:12px;font-weight:800;margin-bottom:7px}.progress{height:8px;background:#e5e7eb;border-radius:9px;overflow:hidden}.progress i{display:block;height:100%;width:0;background:var(--accent);transition:.3s}.streak{align-self:flex-end;margin:12px 0;font-size:12px;color:#6b7280}.question-card{background:#fff;border-radius:25px;padding:23px;box-shadow:var(--shadow)}.tag{display:inline-flex;background:#f0efff;color:var(--accent);padding:6px 9px;border-radius:9px;font-size:10px;font-weight:900;text-transform:uppercase}.question-card h1{font-size:25px;line-height:1.22;margin:16px 0 20px}.answers{display:grid;gap:9px}.answer{width:100%;padding:15px;text-align:left;border:2px solid #eef0f3;background:#f8f9fb;border-radius:15px;color:var(--ink);font-size:14px;font-weight:750;transition:.15s}.answer.correct{border-color:#4ade80;background:#ecfdf5}.answer.wrong{border-color:#f87171;background:#fef2f2}.answer .letter{display:inline-grid;place-items:center;width:27px;height:27px;border-radius:9px;background:#fff;margin-right:8px;color:#6b7280}.feedback{margin-top:12px;padding:14px;border-radius:16px;background:#fff;border:1px solid var(--line);font-size:13px;line-height:1.5}.feedback b{font-size:14px}.feedback small{color:var(--muted)}.next-btn{margin-top:12px}.hidden{display:none!important}.centered{text-align:center;align-items:center;justify-content:center}.result-badge{width:82px;height:82px;border-radius:28px;background:#fff;display:grid;place-items:center;font-size:42px;box-shadow:var(--shadow);margin-bottom:18px}.centered h1{font-size:30px;margin:8px 0}.result-score{font-size:64px;font-weight:950;margin:4px 0 18px}.result-stats{display:grid;grid-template-columns:repeat(3,1fr);width:100%;background:#fff;border-radius:19px;padding:14px;margin-bottom:16px;box-shadow:var(--shadow)}.result-stats div{display:flex;flex-direction:column;gap:4px}.result-stats b{font-size:15px}.result-stats small{font-size:9px;color:var(--muted)}.centered p{color:var(--muted);font-size:13px;line-height:1.5;max-width:430px}.centered .primary,.centered .secondary{width:100%;margin-top:8px}.secondary{background:#fff;color:var(--ink);border:1px solid var(--line);border-radius:18px;padding:15px;font-weight:800}.panel-head{display:flex;align-items:center;gap:12px;padding:5px 0 20px}.panel-head .icon-btn{margin:0}.panel-head h1{font-size:26px;margin:3px 0 0}.panel-card{background:#fff;border:1px solid var(--line);border-radius:19px;padding:16px;margin-bottom:10px;box-shadow:0 5px 18px rgba(17,24,39,.04)}.panel-card h3{margin:0 0 5px}.panel-card p,.panel-card small{color:var(--muted);font-size:11px;margin:0}.category-list{display:grid;grid-template-columns:repeat(2,1fr);gap:10px}.category-list .panel-card{cursor:pointer}.difficulty-row{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}.difficulty-row button{padding:12px 6px;border-radius:14px;background:#fff;border:1px solid var(--line);font-size:11px;font-weight:800}.difficulty-row button.selected{background:var(--ink);color:#fff}@media(max-width:360px){#app{padding-left:13px;padding-right:13px}.question-card h1{font-size:22px}.challenge-grid{gap:7px}}