@import"https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&family=JetBrains+Mono:wght@400;500;600;700&display=swap";:root{font-synthesis:none;text-rendering:optimizeLegibility;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;-webkit-text-size-adjust:100%}body{margin:0;min-width:320px;min-height:100vh}#root{min-height:100vh}*{margin:0;padding:0;box-sizing:border-box}:root{--primary-color: #6366f1;--primary-dark: #4f46e5;--primary-light: #818cf8;--secondary-color: #22d3ee;--success-color: #10b981;--error-color: #ef4444;--warning-color: #f59e0b;--bg-primary: #0f172a;--bg-secondary: #1e293b;--bg-card: #334155;--text-primary: #f1f5f9;--text-secondary: #cbd5e1;--text-muted: #94a3b8;--border-color: #475569;--shadow-color: rgba(0, 0, 0, .5)}body{font-family:Inter,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,sans-serif;background:var(--bg-primary);color:var(--text-primary);min-height:100vh;overflow-x:hidden}.app{min-height:100vh;display:flex;flex-direction:column;position:relative}.background-gradient{position:fixed;inset:0;background:linear-gradient(135deg,var(--bg-primary) 0%,#1a1f3a 25%,#2d1b69 50%,#1a1f3a 75%,var(--bg-primary) 100%);background-size:400% 400%;animation:gradientShift 15s ease infinite;z-index:-1}@keyframes gradientShift{0%{background-position:0% 50%}50%{background-position:100% 50%}to{background-position:0% 50%}}.header{background:#1e293bcc;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border-bottom:1px solid var(--border-color);padding:1rem 2rem;position:sticky;top:0;z-index:100}.header-content{max-width:1200px;margin:0 auto;display:flex;justify-content:space-between;align-items:center}.logo{display:flex;align-items:center;gap:.75rem}.logo-icon{width:32px;height:32px;color:var(--primary-color);animation:pulse 2s infinite}@keyframes pulse{0%,to{transform:scale(1)}50%{transform:scale(1.05)}}.logo h1{font-size:1.75rem;font-weight:800;background:linear-gradient(135deg,var(--primary-color),var(--secondary-color));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.stats{display:flex;gap:2rem}.stat{display:flex;align-items:center;gap:.5rem;padding:.5rem 1rem;background:var(--bg-card);border-radius:12px;border:1px solid var(--border-color)}.stat-icon{width:20px;height:20px;color:var(--primary-light)}.stat span{font-weight:600;color:var(--text-primary)}.settings-btn{background:var(--bg-card);border:1px solid var(--border-color);color:var(--text-primary);padding:.75rem;border-radius:12px;cursor:pointer;display:flex;align-items:center;justify-content:center;transition:all .3s ease}.settings-btn:hover{background:var(--primary-color);border-color:var(--primary-color);transform:rotate(45deg)}.main-content{flex:1;display:flex;align-items:center;justify-content:center;padding:2rem;max-width:1200px;margin:0 auto;width:100%}.challenge-container{width:100%;max-width:600px}.challenge-card{background:#33415599;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border:1px solid var(--border-color);border-radius:24px;padding:2.5rem;box-shadow:0 20px 40px var(--shadow-color)}.problem-display{margin-bottom:2rem}.problem-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:1.5rem}.difficulty-badge{padding:.5rem 1rem;border-radius:8px;font-size:.875rem;font-weight:600;text-transform:uppercase;letter-spacing:.05em}.difficulty-badge[data-difficulty=easy]{background:#10b98133;color:var(--success-color);border:1px solid var(--success-color)}.difficulty-badge[data-difficulty=medium]{background:#f59e0b33;color:var(--warning-color);border:1px solid var(--warning-color)}.difficulty-badge[data-difficulty=hard]{background:#ef444433;color:var(--error-color);border:1px solid var(--error-color)}.operation-badge{padding:.5rem 1rem;background:#6366f133;color:var(--primary-light);border:1px solid var(--primary-color);border-radius:8px;font-size:.875rem;font-weight:500}.problem-text{font-size:2.5rem;font-weight:700;text-align:center;color:var(--text-primary);padding:2rem;background:var(--bg-secondary);border-radius:16px;border:2px solid var(--border-color);letter-spacing:.05em;word-spacing:.2em;font-family:JetBrains Mono,Courier New,monospace}.answer-section{margin-bottom:1.5rem}.input-group{display:flex;gap:1rem}.answer-input{flex:1;padding:1rem 1.5rem;font-size:1.25rem;background:var(--bg-secondary);border:2px solid var(--border-color);border-radius:12px;color:var(--text-primary);transition:all .3s ease;font-family:JetBrains Mono,Courier New,monospace}.answer-input:focus{outline:none;border-color:var(--primary-color);box-shadow:0 0 0 3px #6366f11a}.answer-input:disabled{opacity:.6;cursor:not-allowed}.submit-btn{padding:1rem 2rem;background:linear-gradient(135deg,var(--primary-color),var(--primary-dark));color:#fff;border:none;border-radius:12px;font-size:1rem;font-weight:600;cursor:pointer;transition:all .3s ease}.submit-btn:hover:not(:disabled){transform:translateY(-2px);box-shadow:0 10px 20px #6366f14d}.submit-btn:disabled{opacity:.5;cursor:not-allowed}.feedback{padding:1rem 1.5rem;border-radius:12px;margin-bottom:1.5rem;display:flex;align-items:center;gap:.75rem;font-weight:600;animation:slideIn .3s ease}@keyframes slideIn{0%{transform:translateY(-10px);opacity:0}to{transform:translateY(0);opacity:1}}.feedback.correct{background:#10b98133;color:var(--success-color);border:1px solid var(--success-color)}.feedback.incorrect{background:#ef444433;color:var(--error-color);border:1px solid var(--error-color)}.feedback-icon{animation:sparkle .5s ease}@keyframes sparkle{0%,to{transform:scale(1) rotate(0)}50%{transform:scale(1.2) rotate(180deg)}}.operator-options{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:.75rem;margin-top:1rem}.operator-option{display:flex;align-items:center;padding:.75rem 1rem;background:#ffffff0d;border:2px solid rgba(255,255,255,.1);border-radius:12px;cursor:pointer;transition:all .3s ease}.operator-option:hover{background:#ffffff14;border-color:#fff3}.operator-option.active{background:#6366f11a;border-color:var(--primary-color)}.operator-option input[type=checkbox]{margin-right:.5rem;width:18px;height:18px;cursor:pointer}.operator-content{display:flex;align-items:center;gap:.5rem;flex:1}.operator-icon{display:flex;align-items:center;justify-content:center;width:24px;height:24px}.operator-label{font-weight:500;color:#ffffffe6}.operator-symbol{color:#ffffff80;font-size:.9rem;margin-left:auto}.action-buttons{display:flex;justify-content:space-between;align-items:center;gap:1rem;margin-bottom:1.5rem}.show-answer-btn,.next-btn{padding:.75rem 1.5rem;background:var(--bg-secondary);color:var(--text-primary);border:2px solid var(--border-color);border-radius:12px;font-size:.95rem;font-weight:600;cursor:pointer;display:flex;align-items:center;gap:.5rem;transition:all .3s ease}.show-answer-btn:hover,.next-btn:hover{border-color:var(--primary-color);background:#6366f11a;transform:translateY(-2px)}.next-btn{background:linear-gradient(135deg,var(--primary-color),var(--primary-dark));color:#fff;border:none}.answer-display{display:flex;align-items:center;gap:.75rem;padding:.75rem 1.5rem;background:#22d3ee1a;border:1px solid var(--secondary-color);border-radius:12px}.answer-label{color:var(--text-secondary);font-weight:500}.answer-value{color:var(--secondary-color);font-size:1.25rem;font-weight:700;font-family:JetBrains Mono,Courier New,monospace}.problem-info{display:flex;justify-content:center;gap:2rem;padding-top:1.5rem;border-top:1px solid var(--border-color)}.info-item{color:var(--text-muted);font-size:.875rem;text-transform:uppercase;letter-spacing:.05em;font-weight:500}.settings-container{width:100%;max-width:700px}.settings-card{background:#33415599;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border:1px solid var(--border-color);border-radius:24px;padding:2.5rem;box-shadow:0 20px 40px var(--shadow-color)}.settings-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:2rem}.settings-header h2{font-size:1.75rem;font-weight:700;background:linear-gradient(135deg,var(--primary-color),var(--secondary-color));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.close-btn{background:transparent;border:none;color:var(--text-secondary);cursor:pointer;padding:.5rem;display:flex;align-items:center;justify-content:center;border-radius:8px;transition:all .3s ease}.close-btn:hover{background:var(--bg-secondary);color:var(--primary-color)}.settings-section{margin-bottom:2.5rem}.settings-section h3{font-size:1.25rem;font-weight:600;margin-bottom:1rem;color:var(--text-primary)}.section-description{color:var(--text-secondary);margin-bottom:1.5rem;font-size:.95rem}.difficulty-options{display:flex;flex-direction:column;gap:1rem}.difficulty-option{display:flex;align-items:center;gap:1rem;padding:1.25rem;background:var(--bg-secondary);border:2px solid var(--border-color);border-radius:12px;cursor:pointer;transition:all .3s ease;position:relative;overflow:hidden}.difficulty-option:hover{border-color:var(--accent-color, var(--primary-color));transform:translate(4px)}.difficulty-option.active{border-color:var(--accent-color, var(--primary-color));background:#6366f10d}.option-icon{flex-shrink:0}.option-content{flex:1}.option-content h4{font-size:1.1rem;font-weight:600;margin-bottom:.25rem;color:var(--text-primary)}.option-content p{font-size:.875rem;color:var(--text-secondary)}.active-indicator{position:absolute;left:0;top:0;bottom:0;width:4px;background:var(--accent-color, var(--primary-color))}.slider-container{padding:1.5rem;background:var(--bg-secondary);border-radius:12px;border:1px solid var(--border-color)}.slider-value{display:flex;align-items:baseline;gap:.5rem;margin-bottom:1.5rem;justify-content:center}.value-display{font-size:3rem;font-weight:700;color:var(--primary-color)}.value-label{font-size:1.25rem;color:var(--text-secondary)}.slider-wrapper{position:relative}.slider{width:100%;height:8px;border-radius:4px;background:linear-gradient(to right,var(--primary-color) 0%,var(--primary-color) var(--progress),var(--border-color) var(--progress),var(--border-color) 100%);outline:none;-webkit-appearance:none;appearance:none}.slider::-webkit-slider-thumb{-webkit-appearance:none;appearance:none;width:24px;height:24px;border-radius:50%;background:var(--primary-color);cursor:pointer;border:3px solid var(--bg-secondary);box-shadow:0 0 0 1px var(--primary-color);transition:all .3s ease}.slider::-webkit-slider-thumb:hover{transform:scale(1.2);box-shadow:0 0 20px #6366f180}.slider::-moz-range-thumb{width:24px;height:24px;border-radius:50%;background:var(--primary-color);cursor:pointer;border:3px solid var(--bg-secondary);box-shadow:0 0 0 1px var(--primary-color);transition:all .3s ease}.slider-marks{display:flex;justify-content:space-between;margin-top:.75rem;padding:0 .5rem}.mark{font-size:.75rem;color:var(--text-muted);transition:all .3s ease}.mark.active{color:var(--primary-color);font-weight:600;transform:scale(1.2)}.settings-preview{padding:1.5rem;background:#6366f10d;border:1px solid var(--primary-color);border-radius:12px;margin-bottom:2rem}.settings-preview h4{font-size:1rem;font-weight:600;color:var(--primary-color);margin-bottom:.5rem}.settings-preview p{color:var(--text-secondary);font-size:.95rem;line-height:1.5}.apply-btn{width:100%;padding:1rem 2rem;background:linear-gradient(135deg,var(--primary-color),var(--primary-dark));color:#fff;border:none;border-radius:12px;font-size:1.1rem;font-weight:600;cursor:pointer;transition:all .3s ease}.apply-btn:hover{transform:translateY(-2px);box-shadow:0 10px 30px #6366f166}.footer{padding:2rem;text-align:center;border-top:1px solid var(--border-color);background:#1e293bcc;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px)}.footer p{color:var(--text-secondary);font-size:.875rem;letter-spacing:.05em}@media (max-width: 768px){.header-content{flex-direction:column;gap:1rem}.stats{order:3}.problem-text{font-size:1.75rem;padding:1.5rem}.input-group,.action-buttons{flex-direction:column}.difficulty-option{padding:1rem}.value-display{font-size:2rem}}@media (max-width: 480px){.header{padding:1rem}.challenge-card,.settings-card{padding:1.5rem}.problem-text{font-size:1.5rem;padding:1rem}.stats{gap:1rem}.stat{padding:.5rem .75rem;font-size:.875rem}}