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

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
            padding: 20px;
        }

        .main-container {
            max-width: 1400px;
            margin: 0 auto;
            background: white;
            border-radius: 20px;
            box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
            overflow: hidden;
        }

        .header {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            padding: 30px;
            text-align: center;
        }

        .header h1 {
            font-size: 2.5rem;
            margin-bottom: 10px;
        }

        .tabs {
            display: flex;
            background: #f8f9fa;
            border-bottom: 3px solid #667eea;
        }

        .tab-button {
            flex: 1;
            padding: 20px;
            background: none;
            border: none;
            font-size: 1.2rem;
            font-weight: bold;
            cursor: pointer;
            transition: all 0.3s;
            color: #666;
        }

        .tab-button:hover {
            background: rgba(102, 126, 234, 0.1);
        }

        .tab-button.active {
            background: white;
            color: #667eea;
            border-bottom: 3px solid #667eea;
            margin-bottom: -3px;
        }

        .content {
            display: none;
            padding: 30px;
        }

        .content.active {
            display: block;
        }

        .controls {
            background: #f8f9fa;
            padding: 20px;
            border-radius: 10px;
            margin-bottom: 20px;
        }

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

        .control-group label {
            display: block;
            font-weight: bold;
            margin-bottom: 5px;
            color: #333;
        }

        .control-group select,
        .control-group input {
            width: 100%;
            padding: 10px;
            border: 2px solid #ddd;
            border-radius: 5px;
            font-size: 1rem;
        }

        .preview-container {
            background: #fff;
            border: 3px solid #667eea;
            border-radius: 10px;
            padding: 20px;
            min-height: 400px;
            position: relative;
        }

        .preview-box {
            width: 100%;
            height: 400px;
            border: 2px dashed #ccc;
            position: relative;
        }

        .flex-item,
        .grid-item {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            padding: 20px;
            margin: 5px;
            border-radius: 8px;
            font-weight: bold;
            display: flex;
            align-items: center;
            justify-content: center;
            min-width: 80px;
            min-height: 80px;
            box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
        }

        .code-display {
            background: #2d2d2d;
            color: #f8f8f2;
            padding: 20px;
            border-radius: 10px;
            margin-top: 20px;
            font-family: 'Courier New', monospace;
            overflow-x: auto;
        }

        .code-display pre {
            margin: 0;
            color: #f8f8f2;
        }

        .property {
            color: #66d9ef;
        }

        .value {
            color: #a6e22e;
        }

        .btn-custom {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border: none;
            padding: 10px 20px;
            border-radius: 5px;
            font-weight: bold;
            cursor: pointer;
            margin: 5px;
            transition: transform 0.2s;
        }

        .btn-custom:hover {
            transform: translateY(-2px);
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
        }

        .info-box {
            background: #e7f3ff;
            border-left: 4px solid #2196F3;
            padding: 15px;
            margin: 20px 0;
            border-radius: 5px;
        }

        .info-box h4 {
            color: #2196F3;
            margin-bottom: 10px;
        }

        .row-controls {
            display: flex;
            gap: 10px;
            margin-bottom: 20px;
            flex-wrap: wrap;
        }