:root{font-family:Microsoft YaHei,Inter,-apple-system,BlinkMacSystemFont,Segoe UI,system-ui,sans-serif;line-height:1.6;font-weight:400;--primary-color: #6366f1;--primary-dark: #4f46e5;--primary-light: #818cf8;--accent-color: #06d6a0;--background-primary: #0f172a;--background-secondary: #1e293b;--background-tertiary: #334155;--surface-card: #1e293b;--border-color: #475569;--border-accent: #64748b;--text-primary: #f8fafc;--text-secondary: #cbd5e1;--text-muted: #94a3b8;--shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, .05);--shadow-md: 0 4px 6px -1px rgba(0, 0, 0, .1), 0 2px 4px -1px rgba(0, 0, 0, .06);--shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, .1), 0 4px 6px -2px rgba(0, 0, 0, .05);--shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, .1), 0 10px 10px -5px rgba(0, 0, 0, .04);color-scheme:dark;color:var(--text-primary);background:linear-gradient(135deg,var(--background-primary) 0%,#1a1a2e 100%);font-synthesis:none;text-rendering:optimizeLegibility;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}*{margin:0;padding:0;box-sizing:border-box}body{margin:0;min-height:100vh;overflow:hidden;background:var(--background-primary)}#app{display:flex;height:100vh;width:100vw;gap:2px}#controls{width:350px;background:var(--background-secondary);padding:24px;overflow-y:auto;border-right:2px solid var(--border-color);box-shadow:var(--shadow-lg);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);position:relative}#controls:before{content:"";position:absolute;top:0;left:0;right:0;height:4px;background:linear-gradient(90deg,var(--primary-color),var(--accent-color))}#controls h1{color:var(--text-primary);margin-bottom:24px;font-size:28px;font-weight:700;text-align:center;background:linear-gradient(135deg,var(--primary-light),var(--accent-color));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;text-shadow:0 2px 4px rgba(0,0,0,.1)}.control-group{margin-bottom:24px;padding:20px;background:var(--surface-card);border-radius:12px;border:1px solid var(--border-color);box-shadow:var(--shadow-md);transition:all .3s ease;position:relative;overflow:hidden}.control-group:before{content:"";position:absolute;top:0;left:0;right:0;height:2px;background:linear-gradient(90deg,var(--primary-color),transparent);opacity:0;transition:opacity .3s ease}.control-group:hover{border-color:var(--primary-color);box-shadow:var(--shadow-lg);transform:translateY(-2px)}.control-group:hover:before{opacity:1}.control-group label{display:block;color:var(--text-secondary);margin-bottom:12px;font-size:14px;font-weight:600;letter-spacing:.025em}.control-group input[type=text],.control-group select{width:100%;padding:12px 16px;border:2px solid var(--border-color);border-radius:8px;background:var(--background-tertiary);color:var(--text-primary);font-size:14px;font-family:JetBrains Mono,Consolas,monospace;transition:all .3s ease;-webkit-backdrop-filter:blur(5px);backdrop-filter:blur(5px)}.control-group input[type=text]:focus,.control-group select:focus{outline:none;border-color:var(--primary-color);box-shadow:0 0 0 3px #6366f11a;background:var(--background-secondary)}.control-group select option{background:var(--background-tertiary);color:var(--text-primary);padding:8px}.control-group input[type=range]{width:100%;margin-top:12px;height:6px;border-radius:3px;background:var(--border-color);outline:none;-webkit-appearance:none;appearance:none}.control-group input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;appearance:none;width:20px;height:20px;border-radius:50%;background:linear-gradient(135deg,var(--primary-color),var(--primary-dark));cursor:pointer;box-shadow:var(--shadow-md);transition:all .3s ease}.control-group input[type=range]::-webkit-slider-thumb:hover{transform:scale(1.1);box-shadow:var(--shadow-lg)}.control-group input[type=range]::-moz-range-thumb{width:20px;height:20px;border-radius:50%;background:linear-gradient(135deg,var(--primary-color),var(--primary-dark));cursor:pointer;border:none;box-shadow:var(--shadow-md)}#subdivision-value{color:var(--accent-color);font-weight:700;font-size:16px}button{width:100%;margin-bottom:12px;border-radius:10px;border:2px solid transparent;padding:14px 20px;font-size:14px;font-weight:600;font-family:inherit;background:linear-gradient(135deg,var(--primary-color),var(--primary-dark));color:#fff;cursor:pointer;transition:all .3s ease;position:relative;overflow:hidden;letter-spacing:.025em;box-shadow:var(--shadow-md)}button:before{content:"";position:absolute;top:0;left:-100%;width:100%;height:100%;background:linear-gradient(90deg,transparent,rgba(255,255,255,.2),transparent);transition:left .5s ease}button:hover{background:linear-gradient(135deg,var(--primary-dark),var(--primary-color));transform:translateY(-2px);box-shadow:var(--shadow-lg)}button:hover:before{left:100%}button:active{transform:translateY(0);box-shadow:var(--shadow-sm)}button:focus,button:focus-visible{outline:2px solid var(--primary-color);outline-offset:2px}button#toggle-riemann{background:linear-gradient(135deg,var(--accent-color),#05b894)}button#toggle-riemann:hover{background:linear-gradient(135deg,#05b894,var(--accent-color))}#canvas-container{flex:1;position:relative;background:radial-gradient(ellipse at center,#1a1a2e 0%,var(--background-primary) 100%);border-radius:0 12px 12px 0;overflow:hidden;box-shadow:inset var(--shadow-xl)}.info{margin-top:24px;padding:20px;background:linear-gradient(135deg,var(--surface-card),var(--background-tertiary));border-radius:12px;border:1px solid var(--border-color);box-shadow:var(--shadow-md);position:relative;overflow:hidden}.info:before{content:"";position:absolute;top:0;left:0;right:0;height:3px;background:linear-gradient(90deg,var(--accent-color),var(--primary-color))}.info p{color:var(--text-secondary);font-size:14px;margin:0;line-height:1.6}.info p:first-child{font-weight:600;font-size:16px;color:var(--text-primary)}#integral-value{color:var(--accent-color);font-weight:700;font-size:18px;text-shadow:0 0 10px rgba(6,214,160,.3)}#example-description{margin-top:12px;font-style:italic;color:var(--text-muted);border-left:3px solid var(--primary-color);background:var(--background-tertiary);padding:12px;border-radius:6px;font-size:13px}.instructions{margin-top:24px;padding:20px;background:linear-gradient(135deg,var(--surface-card),var(--background-tertiary));border-radius:12px;border:1px solid var(--border-color);box-shadow:var(--shadow-md);position:relative;overflow:hidden}.instructions:before{content:"";position:absolute;top:0;left:0;right:0;height:3px;background:linear-gradient(90deg,var(--primary-color),var(--accent-color))}.instructions h3{color:var(--text-primary);margin-bottom:16px;font-size:18px;font-weight:700;display:flex;align-items:center;gap:8px}.instructions h3:before{content:"💡";font-size:20px}.instructions ul{color:var(--text-secondary);font-size:13px;padding-left:20px;line-height:1.6}.instructions li{margin-bottom:8px;padding:4px 0;position:relative;transition:color .3s ease}.instructions li:hover{color:var(--text-primary)}.instructions li::marker{color:var(--primary-color)}#loading-indicator{position:absolute;top:50%;left:50%;transform:translate(-50%,-50%);text-align:center;color:var(--text-primary);z-index:1000;background:#0f172ae6;padding:32px;border-radius:16px;border:1px solid var(--border-color);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);box-shadow:var(--shadow-xl)}.loading-spinner{width:48px;height:48px;border:4px solid var(--border-color);border-top:4px solid var(--primary-color);border-right:4px solid var(--accent-color);border-radius:50%;animation:spin 1s linear infinite;margin:0 auto 20px;box-shadow:0 0 20px #6366f14d}#loading-indicator p{color:var(--text-secondary);font-size:14px;font-weight:500;margin:0}@keyframes spin{0%{transform:rotate(0)}to{transform:rotate(360deg)}}@media (max-width: 768px){#app{flex-direction:column}#controls{width:100%;max-height:40vh;border-right:none;border-bottom:2px solid var(--border-color)}#canvas-container{border-radius:0}}#controls::-webkit-scrollbar{width:8px}#controls::-webkit-scrollbar-track{background:var(--background-tertiary);border-radius:4px}#controls::-webkit-scrollbar-thumb{background:linear-gradient(180deg,var(--primary-color),var(--primary-dark));border-radius:4px;transition:background .3s ease}#controls::-webkit-scrollbar-thumb:hover{background:linear-gradient(180deg,var(--primary-light),var(--primary-color))}@keyframes fadeInUp{0%{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}.control-group{animation:fadeInUp .6s ease forwards}.control-group:nth-child(1){animation-delay:.1s}.control-group:nth-child(2){animation-delay:.2s}.control-group:nth-child(3){animation-delay:.3s}.control-group:nth-child(4){animation-delay:.4s}.control-group:nth-child(5){animation-delay:.5s}input:focus,select:focus,button:focus{animation:pulse 2s infinite}@keyframes pulse{0%{box-shadow:0 0 #6366f166}70%{box-shadow:0 0 0 10px #6366f100}to{box-shadow:0 0 #6366f100}}