:root{color:#0f172a;font-synthesis:none;text-rendering:optimizelegibility;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;background-color:#f8fafc;font-family:Inter,system-ui,sans-serif;font-weight:400;line-height:1.5}*{box-sizing:border-box}body{min-height:100vh;color:inherit;background:radial-gradient(circle at top,#e0f2fe 0%,#f8fafc 45%,#f1f5f9 100%);margin:0}#app{min-height:100vh}.app{flex-direction:column;gap:2rem;max-width:960px;margin:0 auto;padding:2.5rem 1.5rem 3rem;display:flex}.topbar{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:1rem;display:flex}.nav-buttons{align-items:center;gap:1rem;display:flex}h1{margin:0;font-size:2.5rem;line-height:1.1}.subtitle{color:#475569;margin:.4rem 0 0}.deck{color:#0f172a;background:#fff;border:1px solid #e2e8f0;border-radius:999px;padding:.5rem 1rem;font-weight:600;box-shadow:0 8px 20px #0f172a14}.nav-link{color:#fff;background:linear-gradient(135deg,#fbbf24,#f97316);border-radius:999px;align-items:center;gap:.4rem;padding:.6rem 1.2rem;font-size:.95rem;font-weight:600;text-decoration:none;transition:transform .15s,box-shadow .2s;display:inline-flex;box-shadow:0 8px 20px #0f172a1f}.nav-link:hover{transform:translateY(-1px);box-shadow:0 12px 28px #0f172a29}main{gap:2rem;display:grid}.card-area{place-items:center;gap:1rem;display:grid}.card{cursor:pointer;perspective:1200px;background:0 0;border:none;width:min(700px,100%);height:450px;padding:0}.card:focus-visible{border-radius:24px;outline:3px solid #38bdf8}.card-inner{width:100%;height:100%;transform-style:preserve-3d;border-radius:24px;transition:transform .6s;position:relative;box-shadow:0 25px 60px #0f172a33}.card-inner.is-flipped{transform:rotateY(180deg)}.card-face{backface-visibility:hidden;background:#fff;border-radius:24px;flex-direction:column;gap:.75rem;padding:2.5rem;display:flex;position:absolute;inset:0;overflow-y:auto}.card-front{border:1px solid #e2e8f0}.card-back{color:#f8fafc;background:#0f172a;transform:rotateY(180deg)}.label{letter-spacing:.12em;text-transform:uppercase;color:inherit;opacity:.6;font-size:.85rem}.card-front .label{color:#64748b}.card-front h2{margin:0;font-size:1.75rem}.card-back p{margin:0;font-size:1.2rem;line-height:1.6}.hint{color:#64748b;margin:0;font-size:.95rem}.controls{background:#fff;border:1px solid #e2e8f0;border-radius:20px;gap:1.25rem;padding:1.5rem;display:grid;box-shadow:0 12px 30px #0f172a14}.buttons{flex-wrap:wrap;justify-content:center;gap:.75rem;display:flex}.buttons.secondary button{color:#0f172a;background:#f1f5f9}button{color:#f8fafc;cursor:pointer;background:#0f172a;border:1px solid #0000;border-radius:999px;padding:.7rem 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.2s;display:flex}.option:hover:not(:disabled){background:#e0f2fe;border-color:#38bdf8;transform:translate(4px)}.option.selected{background:#e0e7ff;border-color:#6366f1}.option.correct{background:#dcfce7;border-color:#22c55e}.option.incorrect{background:#fee2e2;border-color:#ef4444}.option:disabled{cursor:not-allowed}.option-letter{color:#0f172a;background:#cbd5e1;border-radius:6px;flex-shrink:0;justify-content:center;align-items:center;min-width:28px;height:28px;font-size:.9rem;font-weight:700;display:inline-flex}.option.selected .option-letter{color:#fff;background:#6366f1}.option.correct .option-letter{color:#fff;background:#22c55e}.option.incorrect .option-letter{color:#fff;background:#ef4444}.option-text{flex:1}.icon{flex-shrink:0;margin-left:auto;font-size:1.2rem}.feedback{text-align:center;border-radius:12px;padding:1rem;font-weight:600;animation:.3s slideIn}.feedback.correct{color:#166534;background:#dcfce7;border:1px solid #22c55e}.feedback.incorrect{color:#991b1b;background:#fee2e2;border:1px solid #ef4444}@keyframes slideIn{0%{opacity:0;transform:translateY(-10px)}to{opacity:1;transform:translateY(0)}}.score-preview{text-align:center;color:#475569;border-top:1px solid #e2e8f0;padding:.75rem 0;font-size:1rem}.results-container{justify-content:center;place-items:center;min-height:60vh;display:flex}.results-card{text-align:center;background:#fff;border:1px solid #e2e8f0;border-radius:20px;flex-direction:column;gap:1.5rem;width:100%;max-width:500px;padding:3rem;display:flex;box-shadow:0 25px 60px #0f172a33}.results-card h2{color:#0f172a;margin:0;font-size:1.75rem}.score-large{justify-content:center;align-items:center;gap:1rem;display:flex}.score-number{background:linear-gradient(135deg,#38bdf8,#6366f1);-webkit-text-fill-color:transparent;-webkit-background-clip:text;background-clip:text;font-size:3rem;font-weight:700}.score-percentage{color:#64748b;font-size:2rem;font-weight:600}.result-message{color:#0f172a;margin:0;font-size:1.1rem;font-weight:600;line-height:1.6}.results-details{justify-content:center;gap:1rem;display:flex}.result-item{background:#f8fafc;border-radius:12px;flex-direction:column;flex:1;gap:.5rem;padding:1rem;display:flex}.result-label{text-transform:uppercase;letter-spacing:.12em;color:#64748b;font-size:.85rem;font-weight:600}.result-value{color:#0f172a;font-size:1.75rem;font-weight:700}.result-value.correct-count{color:#22c55e}.result-value.incorrect-count{color:#ef4444}.button-group{flex-direction:column;gap:.75rem;margin-top:1rem;display:flex}.button-group button{padding:.9rem 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