body {
            font-family: 'SimSun', '宋体', serif;
            margin: 0;
            padding: 20px;
            background: #F4F3EC;
            color: #0C0302;
            min-height: 100vh;
        }

        .container {
            max-width: 1200px;
            margin: 0 auto;
            display: flex;
            gap: 20px;
            align-items: flex-start;
        }

        .main-content {
            flex: 1;
            background: white;
            border-radius: 8px;
            padding: 20px;
            box-shadow: 0 2px 10px rgba(0,0,0,0.1);
        }

        .title {
            font-size: 32px;
            font-weight: bold;
            color: #FF5600;
            text-align: center;
            margin-bottom: 30px;
        }

        .canvas-container {
            position: relative;
            width: 100%;
            height: 500px;
            border: 2px solid #FF5600;
            border-radius: 8px;
            background: white;
            margin-bottom: 20px;
        }

        #geometryCanvas {
            width: 100%;
            height: 100%;
            display: block;
        }

        .controls {
            width: 300px;
            background: white;
            border-radius: 8px;
            padding: 20px;
            box-shadow: 0 2px 10px rgba(0,0,0,0.1);
        }

        .control-section {
            margin-bottom: 25px;
            padding-bottom: 20px;
            border-bottom: 1px solid #eee;
        }

        .control-section:last-child {
            border-bottom: none;
        }

        .section-title {
            font-size: 18px;
            font-weight: bold;
            color: #FF5600;
            margin-bottom: 15px;
        }

        .slider-group {
            margin-bottom: 15px;
        }

        .slider-label {
            display: block;
            font-size: 16px;
            color: #74706E;
            margin-bottom: 8px;
        }

        .slider {
            width: 100%;
            height: 6px;
            border-radius: 3px;
            background: #ddd;
            outline: none;
            -webkit-appearance: none;
        }

        .slider::-webkit-slider-thumb {
            -webkit-appearance: none;
            appearance: none;
            width: 20px;
            height: 20px;
            border-radius: 50%;
            background: #FF5600;
            cursor: pointer;
        }

        .slider::-moz-range-thumb {
            width: 20px;
            height: 20px;
            border-radius: 50%;
            background: #FF5600;
            cursor: pointer;
            border: none;
        }

        .value-display {
            font-size: 16px;
            color: #0C0302;
            font-weight: bold;
            margin-top: 5px;
        }

        .button-group {
            display: flex;
            gap: 10px;
            flex-wrap: wrap;
        }

        .btn {
            padding: 10px 15px;
            border: none;
            border-radius: 5px;
            background: #FF5600;
            color: white;
            font-size: 16px;
            cursor: pointer;
            transition: background 0.3s;
            font-family: inherit;
        }

        .btn:hover {
            background: #FF8941;
        }

        .btn.secondary {
            background: #74706E;
        }

        .btn.secondary:hover {
            background: #5a5654;
        }

        .preset-buttons {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 8px;
        }

        .preset-btn {
            padding: 8px 12px;
            font-size: 14px;
        }

        .angle-display {
            background: #f8f9fa;
            padding: 15px;
            border-radius: 8px;
            margin-top: 20px;
        }

        .angle-row {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 8px;
            font-size: 18px;
        }

        .angle-row:last-child {
            margin-bottom: 0;
            font-weight: bold;
            border-top: 1px solid #ddd;
            padding-top: 8px;
        }

        .angle-alpha { color: #e53e3e; }
        .angle-beta { color: #3182ce; }
        .angle-gamma { color: #38a169; }
        .angle-sum { color: #FF5600; }

        .step-indicator {
            text-align: center;
            font-size: 18px;
            color: #FF5600;
            font-weight: bold;
            margin-bottom: 15px;
            min-height: 25px;
        }

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

        @media (max-width: 768px) {
            .container {
                flex-direction: column;
            }
            
            .controls {
                width: 100%;
            }
            
            .title {
                font-size: 28px;
            }
        }