:root{--bg-primary: #0f0f23;--bg-secondary: #151537;--bg-tertiary: #1e1e42;--text-primary: #ffffff;--text-secondary: #cccccc;--text-muted: #888888;--accent-primary: #00c9ff;--accent-secondary: #0099cc;--success: #00ff88;--error: #ff4444;--warning: #ffaa00;--border: #333366;--shadow: rgba(0, 0, 0, .3)}*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Fira Sans,Droid Sans,Helvetica Neue,sans-serif;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;background:var(--bg-primary);color:var(--text-primary);line-height:1.6}#root{min-height:100vh}.container{max-width:1200px;margin:0 auto;padding:0 1rem}.container-fluid{padding:0 1rem}.card{background:var(--bg-secondary);border-radius:12px;border:1px solid var(--border);box-shadow:0 4px 6px var(--shadow);overflow:hidden}.card-header{padding:1.5rem;border-bottom:1px solid var(--border);background:var(--bg-tertiary)}.card-body{padding:1.5rem}.card-footer{padding:1rem 1.5rem;border-top:1px solid var(--border);background:var(--bg-tertiary)}.btn{display:inline-flex;align-items:center;justify-content:center;padding:.75rem 1.5rem;border-radius:8px;border:none;font-size:.95rem;font-weight:500;text-decoration:none;cursor:pointer;transition:all .2s ease;gap:.5rem;min-height:44px}.btn:disabled{opacity:.6;cursor:not-allowed}.btn-primary{background:linear-gradient(45deg,var(--accent-primary),var(--accent-secondary));color:#fff}.btn-primary:hover:not(:disabled){transform:translateY(-2px);box-shadow:0 8px 16px #00c9ff4d}.btn-secondary{background:var(--bg-tertiary);color:var(--text-primary);border:1px solid var(--border)}.btn-secondary:hover:not(:disabled){background:var(--border)}.btn-success{background:var(--success);color:var(--bg-primary)}.btn-error{background:var(--error);color:#fff}.btn-warning{background:var(--warning);color:var(--bg-primary)}.btn-lg{padding:1rem 2rem;font-size:1.1rem}.btn-sm{padding:.5rem 1rem;font-size:.875rem;min-height:36px}.form-group{margin-bottom:1.5rem}.form-label{display:block;margin-bottom:.5rem;font-weight:500;color:var(--text-secondary)}.form-control{width:100%;padding:.75rem;border:1px solid var(--border);border-radius:6px;background:var(--bg-tertiary);color:var(--text-primary);font-size:1rem}.form-control:focus{outline:none;border-color:var(--accent-primary);box-shadow:0 0 0 3px #00c9ff1a}.progress{width:100%;height:8px;background:var(--bg-tertiary);border-radius:4px;overflow:hidden}.progress-bar{height:100%;background:linear-gradient(45deg,var(--accent-primary),var(--accent-secondary));border-radius:4px;transition:width .3s ease}.grid{display:grid;gap:1.5rem}.grid-2{grid-template-columns:repeat(auto-fit,minmax(300px,1fr))}.grid-3{grid-template-columns:repeat(auto-fit,minmax(250px,1fr))}.grid-4{grid-template-columns:repeat(auto-fit,minmax(200px,1fr))}.flex{display:flex}.flex-col{flex-direction:column}.items-center{align-items:center}.justify-center{justify-content:center}.justify-between{justify-content:space-between}.gap-2{gap:.5rem}.gap-4{gap:1rem}.gap-6{gap:1.5rem}.mb-2{margin-bottom:.5rem}.mb-4{margin-bottom:1rem}.mb-6{margin-bottom:1.5rem}.mb-8{margin-bottom:2rem}.mt-2{margin-top:.5rem}.mt-4{margin-top:1rem}.mt-6{margin-top:1.5rem}.mt-8{margin-top:2rem}.text-center{text-align:center}.text-sm{font-size:.875rem}.text-lg{font-size:1.125rem}.text-xl{font-size:1.25rem}.text-2xl{font-size:1.5rem}.text-3xl{font-size:1.875rem}.text-muted{color:var(--text-muted)}.text-success{color:var(--success)}.text-error{color:var(--error)}.text-warning{color:var(--warning)}.font-bold{font-weight:700}.question-option{padding:1rem;border:2px solid var(--border);border-radius:8px;cursor:pointer;transition:all .2s ease;background:var(--bg-tertiary);color:var(--text-primary)}.question-option:hover{border-color:var(--accent-primary);transform:translateY(-2px)}.question-option.selected{border-color:var(--accent-primary);background:#00c9ff1a}.question-option.correct{border-color:var(--success);background:#00ff881a}.question-option.incorrect{border-color:var(--error);background:#ff44441a}.explanation{background:var(--bg-tertiary);border:1px solid var(--border);border-radius:8px;padding:1.5rem;margin-top:1rem;animation:slideIn .3s ease-out}@keyframes slideIn{0%{opacity:0;transform:translateY(-10px)}to{opacity:1;transform:translateY(0)}}.stat-card{text-align:center}.stat-number{font-size:2.5rem;font-weight:700;color:var(--accent-primary);display:block}.stat-label{color:var(--text-secondary);font-size:.875rem;margin-top:.25rem}.spinner{border:2px solid var(--border);border-top:2px solid var(--accent-primary);border-radius:50%;width:24px;height:24px;animation:spin 1s linear infinite}@keyframes spin{0%{transform:rotate(0)}to{transform:rotate(360deg)}}@media (max-width: 768px){.container{padding:0 .75rem}.card-body,.card-header{padding:1rem}.btn{padding:.625rem 1.25rem}.grid-2,.grid-3,.grid-4{grid-template-columns:1fr}.text-3xl{font-size:1.5rem}.text-2xl{font-size:1.25rem}}::-webkit-scrollbar{width:8px}::-webkit-scrollbar-track{background:var(--bg-secondary)}::-webkit-scrollbar-thumb{background:var(--border);border-radius:4px}::-webkit-scrollbar-thumb:hover{background:var(--accent-secondary)}