* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'SimSun', '宋体', serif;
            background: linear-gradient(135deg, #0f172a 0%, #1e293b 50%, #334155 100%);
            min-height: 100vh;
            padding: 20px;
        }

        .container {
            background: rgba(255, 255, 255, 0.98);
            border-radius: 20px;
            padding: 30px;
            box-shadow: 0 25px 80px rgba(0, 0, 0, 0.25);
            backdrop-filter: blur(10px);
            max-width: 1400px;
            margin: 0 auto;
            border: 1px solid rgba(255, 255, 255, 0.1);
        }

        h1 {
            text-align: center;
            color: #1e293b;
            margin-bottom: 30px;
            font-size: 2.8em;
            background: linear-gradient(135deg, #06b6d4, #0891b2, #0e7490);
            -webkit-background-clip: text;
            background-clip: text;
            -webkit-text-fill-color: transparent;
            font-weight: 700;
        }

        .global-controls {
            text-align: center;
            margin: 30px 0;
            padding: 25px;
            background: linear-gradient(135deg, #e3f2fd, #bbdefb);
            border-radius: 15px;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
        }

        .global-controls h3 {
            margin-bottom: 20px;
            color: #2d3748;
            font-size: 1.3em;
        }

        .method-section {
            margin: 50px 0;
            padding: 30px;
            background: #fff;
            border-radius: 20px;
            box-shadow: 0 15px 35px rgba(0, 0, 0, 0.1);
            border: 3px solid #e2e8f0;
        }

        .method-header {
            text-align: center;
            margin-bottom: 25px;
        }

        .method-title {
            font-size: 2em;
            color: white;
            margin-bottom: 10px;
            padding: 15px;
            background: linear-gradient(135deg, #0e7490, #0891b2, #06b6d4);
            border-radius: 15px;
            box-shadow: 0 8px 20px rgba(6, 182, 212, 0.3);
            font-weight: 600;
        }

        .method-description {
            font-size: 1.1em;
            color: #4a5568;
            font-style: italic;
        }

        .animation-area {
            width: 100%;
            height: 600px;
            border: 3px solid #2196f3;
            border-radius: 15px;
            margin: 25px 0;
            background: linear-gradient(135deg, #e3f2fd, #f0f9ff);
            position: relative;
            overflow: hidden;
            box-shadow: inset 0 2px 10px rgba(0, 0, 0, 0.1);
        }

        .controls {
            display: flex;
            justify-content: center;
            gap: 15px;
            margin: 25px 0;
            flex-wrap: wrap;
        }

        .btn {
            padding: 12px 25px;
            border: none;
            border-radius: 30px;
            cursor: pointer;
            font-size: 16px;
            font-weight: 600;
            transition: all 0.3s ease;
            text-transform: uppercase;
            letter-spacing: 1px;
            min-width: 120px;
        }

        .btn-primary {
            background: linear-gradient(135deg, #06b6d4, #0891b2);
            color: white;
            border: 1px solid rgba(6, 182, 212, 0.3);
        }

        .btn-primary:hover {
            transform: translateY(-3px);
            box-shadow: 0 10px 25px rgba(6, 182, 212, 0.4);
        }

        .btn-secondary {
            background: linear-gradient(135deg, #10b981, #059669);
            color: white;
            border: 1px solid rgba(16, 185, 129, 0.3);
        }

        .btn-secondary:hover {
            transform: translateY(-3px);
            box-shadow: 0 10px 25px rgba(16, 185, 129, 0.4);
        }

        .btn-warning {
            background: linear-gradient(135deg, #f59e0b, #d97706);
            color: white;
            border: 1px solid rgba(245, 158, 11, 0.3);
        }

        .btn-warning:hover {
            transform: translateY(-3px);
            box-shadow: 0 10px 25px rgba(245, 158, 11, 0.4);
        }

        .info-panel {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 20px;
            margin: 25px 0;
        }

        .formula-display {
            background: linear-gradient(135deg, #e3f2fd, #bbdefb);
            border: 2px solid #1976d2;
            border-radius: 15px;
            padding: 20px;
            text-align: center;
            font-size: 1.2em;
            min-height: 80px;
            display: flex;
            align-items: center;
            justify-content: center;
            box-shadow: 0 5px 15px rgba(25, 118, 210, 0.2);
        }

        .step-info {
            background: linear-gradient(135deg, #f0f9ff, #e1f5fe);
            border: 2px solid #2196f3;
            border-radius: 15px;
            padding: 20px;
            font-size: 16px;
            line-height: 1.6;
            box-shadow: 0 5px 15px rgba(33, 150, 243, 0.2);
        }

        .step-info h4 {
            color: #1976d2;
            margin-bottom: 10px;
            font-size: 1.1em;
        }

        .debug-mode {
            position: absolute;
            top: 10px;
            right: 10px;
            background: rgba(255, 0, 0, 0.9);
            color: white;
            padding: 8px 12px;
            border-radius: 8px;
            font-size: 12px;
            font-family: monospace;
            z-index: 1000;
            display: none;
            box-shadow: 0 4px 10px rgba(0, 0, 0, 0.3);
        }

        /* 平板设备适配 */
        @media (max-width: 1024px) {
            .info-panel {
                grid-template-columns: 1fr;
                gap: 20px;
            }
            
            .animation-area {
                height: 500px;
            }
            
            .container {
                padding: 20px;
                margin: 10px;
            }
            
            .global-controls {
                gap: 15px;
            }
        }

        /* 移动端适配 */
        @media (max-width: 768px) {
            body {
                padding: 10px;
            }
            
            h1 {
                font-size: 2.2em;
                margin-bottom: 20px;
            }
            
            .container {
                padding: 15px;
                border-radius: 15px;
                margin: 5px;
            }
            
            .animation-area {
                height: 350px;
                margin-bottom: 15px;
            }
            
            .btn {
                padding: 12px 16px;
                font-size: 14px;
                min-width: 80px;
                min-height: 44px; /* 移动端最小触摸目标 */
            }
            
            .global-controls {
                flex-wrap: wrap;
                gap: 10px;
                justify-content: center;
            }
            
            .step-info {
                padding: 15px;
                margin-bottom: 15px;
            }
            
            .formula-display {
                padding: 15px;
                font-size: 14px;
            }
        }

        /* 小屏移动设备适配 */
        @media (max-width: 480px) {
            h1 {
                font-size: 1.8em;
            }
            
            .animation-area {
                height: 300px;
            }
            
            .btn {
                padding: 10px 12px;
                font-size: 12px;
                min-width: 70px;
            }
            
            .step-info h4 {
                font-size: 16px;
            }
            
            .step-info {
                padding: 12px;
            }
        }

        /* 触摸设备优化 */
        @media (hover: none) and (pointer: coarse) {
            .btn:hover {
                transform: none;
            }
            
            .btn:active {
                transform: scale(0.95);
                transition: transform 0.1s ease;
            }
        }

        /* 移动端专用样式 */
        .mobile-device {
            -webkit-text-size-adjust: 100%;
            -webkit-tap-highlight-color: transparent;
        }
        
        .mobile-device .animation-area {
            -webkit-overflow-scrolling: touch;
            overscroll-behavior: contain;
        }
        
        .mobile-device .btn {
            -webkit-appearance: none;
            appearance: none;
            -webkit-touch-callout: none;
            -webkit-user-select: none;
            user-select: none;
        }
        
        .mobile-device svg {
            -webkit-user-select: none;
            -moz-user-select: none;
            -ms-user-select: none;
            user-select: none;
        }

        /* 性能优化 */
        .animation-area svg {
            will-change: transform;
            backface-visibility: hidden;
            -webkit-backface-visibility: hidden;
        }

        /* 高DPI屏幕优化 */
        @media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi) {
            .dimension-text, .formula-display {
                -webkit-font-smoothing: antialiased;
                -moz-osx-font-smoothing: grayscale;
            }
        }

        /* 几何元素样式优化 - 蓝色学术配色方案 */
        .trapezoid {
            fill: rgba(33, 150, 243, 0.8);
            stroke: #1976d2;
            stroke-width: 3;
            filter: drop-shadow(2px 2px 4px rgba(0, 0, 0, 0.2));
        }

        .trapezoid-copy {
            fill: rgba(66, 165, 245, 0.8);
            stroke: #42a5f5;
            stroke-width: 3;
            filter: drop-shadow(2px 2px 4px rgba(0, 0, 0, 0.2));
        }

        .parallelogram {
            fill: rgba(76, 175, 80, 0.8);
            stroke: #388e3c;
            stroke-width: 3;
            filter: drop-shadow(2px 2px 4px rgba(0, 0, 0, 0.2));
        }

        .rectangle {
            fill: rgba(144, 202, 249, 0.8);
            stroke: #90caf9;
            stroke-width: 3;
            filter: drop-shadow(2px 2px 4px rgba(0, 0, 0, 0.2));
        }

        .triangle {
            fill: rgba(255, 152, 0, 0.8);
            stroke: #f57c00;
            stroke-width: 3;
            filter: drop-shadow(2px 2px 4px rgba(0, 0, 0, 0.2));
        }
        
        .triangle-dashed {
            fill: none;
            stroke: #f57c00;
            stroke-width: 3;
            stroke-dasharray: 8,4;
            opacity: 0.9;
        }
        
        .move-arrow {
            fill: none;
            stroke: #1976d2;
            stroke-width: 2;
            stroke-dasharray: 6,3;
            opacity: 0.7;
        }

        .dimension-line {
            stroke: #2d3748;
            stroke-width: 2;
            fill: none;
        }

        .dimension-text {
            font-family: Arial, sans-serif;
            font-size: 16px;
            font-weight: bold;
            fill: #2d3748;
            text-anchor: middle;
            dominant-baseline: middle;
            background: white;
        }

        .helper-line {
            stroke: #a0aec0;
            stroke-width: 2;
            stroke-dasharray: 8,4;
            fill: none;
        }

        .highlight {
            animation: pulse 2s infinite;
        }

        .footer {
            background: linear-gradient(to right);
            color: #0c0302;
            text-align: center;
            padding: 10px;
            margin-top: 15px;
            border-radius: 0 0 10px 10px;
        }

        @keyframes pulse {
            0% { opacity: 0.8; }
            50% { opacity: 1; }
            100% { opacity: 0.8; }
        }