:root{--bg-dark:#0f172a;--bg-mid:#1f2937;--surface:#ffffff1f;--surface-strong:#ffffff2e;--surface-soft:#ffffff14;--text:#e2e8f0;--text-strong:#111827;--text-soft:#cbd5f1;--accent:#f59e0b;--accent-strong:#d97706;--accent-soft:#fde68a;--border:#ffffff38;--shadow:0 32px 120px #0f172a3d}@keyframes fadeIn{0%{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}@keyframes slideInLeft{0%{opacity:0;transform:translate(-30px)}to{opacity:1;transform:translate(0)}}@keyframes slideInRight{0%{opacity:0;transform:translate(30px)}to{opacity:1;transform:translate(0)}}@keyframes pulse{0%{transform:scale(1)}50%{transform:scale(1.05)}to{transform:scale(1)}}@keyframes glow{0%{box-shadow:0 0 5px #f59e0b80}50%{box-shadow:0 0 20px #f59e0bcc}to{box-shadow:0 0 5px #f59e0b80}}*{box-sizing:border-box;margin:0;padding:0}html{scroll-behavior:smooth}body{min-height:100vh;color:var(--text);background:radial-gradient(circle at top left, #6366f133, transparent 28%), radial-gradient(circle at bottom right, #8b5cf62e, transparent 24%), linear-gradient(180deg, var(--bg-dark) 0%, var(--bg-mid) 100%);padding:24px;font-family:Inter,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif}img{max-width:100%;display:block}.app-shell,.app,.question-box,.result-box,.chart-container,.glass,.topic-card-content{color:#111827}button,input,textarea,select{font:inherit}.app-shell{max-width:1080px;box-shadow:var(--shadow);-webkit-backdrop-filter:blur(24px);backdrop-filter:blur(24px);background:#ffffff2e;border:1px solid #ffffff3d;border-radius:36px;margin:0 auto;padding:28px;animation:.8s ease-out fadeIn}.app{box-shadow:var(--shadow);-webkit-backdrop-filter:blur(20px);backdrop-filter:blur(20px);color:#111827;background:#ffffff38;border:1px solid #ffffff3d;border-radius:32px;margin:0 auto;padding:34px;animation:1s ease-out .2s both fadeIn}nav{flex-wrap:wrap;justify-content:center;gap:14px;margin-bottom:28px;display:flex}nav a{color:var(--text-strong);background:#ffffffdb;border:1px solid #94a3b83d;border-radius:999px;padding:12px 20px;font-weight:700;text-decoration:none;transition:transform .2s,background .2s,box-shadow .2s;box-shadow:0 14px 32px #0f172a14}nav a:hover{background:#fff;transform:translateY(-2px)}.header-section{text-align:center;margin-bottom:32px;padding:0 12px}.header-section h1{color:#eef2ff;letter-spacing:-1px;margin-bottom:12px;font-size:clamp(2.4rem,5vw,3.4rem)}.header-subtitle{color:var(--text-soft);font-size:1rem;line-height:1.8}.topic-selection{margin-top:10px}.topic-grid{grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:22px;display:grid}button.topic-card{text-align:left;-webkit-backdrop-filter:blur(18px);backdrop-filter:blur(18px);background:#ffffff38;border:1px solid #ffffff42;border-radius:28px;width:100%;transition:transform .25s,border-color .25s,box-shadow .25s;overflow:hidden;box-shadow:0 24px 70px #0f172a29}button.topic-card:hover{border-color:#ffffff5c;animation:.6s ease-in-out pulse;transform:translateY(-6px)scale(1.02);box-shadow:0 32px 90px #0f172a29}.topic-image{object-fit:cover;border-radius:6%;width:100%;height:180px}.topic-card-content{padding:24px 24px 22px}.topic-card-content h3{color:#0f172a;margin-bottom:10px;font-size:1.35rem}.topic-card-content p{color:#334155;font-size:.98rem;line-height:1.75}.quiz-header{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:16px;margin-bottom:26px;display:flex}.quiz-header h1{color:#eef2ff;margin:0;font-size:clamp(1.9rem,3.2vw,2.6rem)}button.change-topic-btn,button.retake-btn{color:#111827;background:#ffffff2e;border:1px solid #fff3;border-radius:999px;width:auto;padding:12px 20px;font-size:.95rem;font-weight:700}button.change-topic-btn:hover,button.retake-btn:hover{background:#ffffff4d}.timer-section{gap:16px;margin-bottom:28px;display:grid}.timer-display{-webkit-backdrop-filter:blur(18px);backdrop-filter:blur(18px);background:linear-gradient(135deg,#fffc,#fffae7ad);border:1px solid #f9731640;border-radius:24px;justify-content:space-between;align-items:center;padding:18px 22px;display:flex;box-shadow:0 18px 55px #f59e0b2e}.timer-label{text-transform:uppercase;letter-spacing:.16em;color:#7c2d12;font-size:.78rem;font-weight:700}.timer-value{color:#c2410c;letter-spacing:.03em;font-size:2rem}.timer-bar-container{background:#ffffff42;border:1px solid #f973162e;border-radius:999px;width:100%;height:14px;overflow:hidden}.timer-bar{border-radius:inherit;background:linear-gradient(90deg,#f59e0b,#facc15);height:100%;transition:width .25s;box-shadow:0 0 14px #facc154d}.question-box{-webkit-backdrop-filter:blur(22px);backdrop-filter:blur(22px);background:#ffffff94;border:1px solid #ffffff73;border-radius:32px;margin-top:10px;padding:32px;animation:.6s ease-out slideInLeft;box-shadow:0 20px 60px #0f172a1f}.question-box h3{color:#0f172a;margin-bottom:18px;font-size:1.2rem}.question-box p{color:#334155;margin-bottom:28px;font-size:1.05rem;line-height:1.75}button{color:#fff;cursor:pointer;background:linear-gradient(135deg, var(--accent), var(--accent-strong));border:none;border-radius:18px;width:100%;max-width:100%;margin:12px auto;padding:14px 28px;font-family:inherit;font-size:1rem;font-weight:700;transition:transform .2s,box-shadow .2s,background .2s;display:block;box-shadow:0 14px 40px #f9731633}button:hover{animation:1s ease-in-out infinite glow;transform:translateY(-2px);box-shadow:0 18px 45px #6366f140}button:active{transform:translateY(0)}.result-box{color:var(--text-strong);-webkit-backdrop-filter:blur(18px);backdrop-filter:blur(18px);background:#ffffff29;border:1px solid #fff3;border-radius:32px;padding:36px 32px;animation:.7s ease-out slideInRight;box-shadow:0 24px 80px #0f172a29}.result-box h2{color:#111827;margin-bottom:28px}.result-stats{grid-template-columns:repeat(3,minmax(100px,1fr));gap:16px;margin-bottom:28px;display:grid}.stat-item{-webkit-backdrop-filter:blur(16px);backdrop-filter:blur(16px);text-align:center;background:#ffffff2e;border:1px solid #ffffff2e;border-radius:24px;padding:18px 16px}.stat-label{text-transform:uppercase;letter-spacing:.16em;opacity:.9;margin-bottom:10px;font-size:.82rem;display:block}.stat-value{font-size:1.45rem;font-weight:800}.chart-container{-webkit-backdrop-filter:blur(16px);backdrop-filter:blur(16px);background:#ffffff29;border:1px solid #ffffff29;border-radius:28px;max-width:420px;margin:0 auto 28px;padding:18px}.chart-container canvas{width:100%!important;height:auto!important}.result-message{margin-bottom:26px;font-size:1rem;line-height:1.8}.retake-btn{color:#111827;background:linear-gradient(135deg,#f97316 0%,#facc15 100%);width:auto;padding:14px 28px}.retake-btn:hover{background:linear-gradient(135deg,#ea580c 0%,#f59e0b 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