:root {
            --primary-color: #4285f4;
            --hover-color: #3367d6;
            --border-color: #ddd;
            --toolbar-bg: #f5f5f5;
            --tab-bg: #e0e0e0;
            --tab-active-bg: #fff;
        }

        body {
            margin: 0;
            padding: 0;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            height: 100vh;
            display: flex;
            flex-direction: column;
            color: #333;
        }

        .tabs-container {
            display: flex;
            background: var(--toolbar-bg);
            padding: 5px 5px 0 5px;
            border-bottom: 1px solid var(--border-color);
            overflow-x: auto;
        }

        .tab {
            padding: 8px 15px;
            margin-right: 5px;
            background: var(--tab-bg);
            border: 1px solid var(--border-color);
            border-bottom: none;
            border-radius: 5px 5px 0 0;
            cursor: pointer;
            position: relative;
            white-space: nowrap;
            display: flex;
            align-items: center;
            max-width: 200px;
        }

        .tab.active {
            background: var(--tab-active-bg);
            border-bottom: 1px solid var(--tab-active-bg);
            margin-bottom: -1px;
            font-weight: bold;
        }

        .tab-title {
            overflow: hidden;
            text-overflow: ellipsis;
        }

        .tab-close {
            margin-left: 8px;
            color: #888;
            font-size: 14px;
            flex-shrink: 0;
        }

        .tab-close:hover {
            color: #333;
        }

        .add-tab {
            padding: 8px 15px;
            background: var(--tab-bg);
            border: 1px solid var(--border-color);
            border-radius: 5px 5px 0 0;
            cursor: pointer;
            margin-left: 5px;
            flex-shrink: 0;
        }

        .toolbar {
            display: flex;
            background: var(--toolbar-bg);
            padding: 8px;
            border-bottom: 1px solid var(--border-color);
            flex-wrap: wrap;
            gap: 5px;
        }

        .toolbar-group {
            display: flex;
            border-right: 1px solid var(--border-color);
            padding-right: 10px;
            margin-right: 10px;
        }

        .toolbar-group:last-child {
            border-right: none;
            margin-right: 0;
        }

        .toolbar-btn {
            background: none;
            border: 1px solid transparent;
            border-radius: 3px;
            padding: 5px 8px;
            cursor: pointer;
            color: #555;
            font-size: 14px;
        }

        .toolbar-btn:hover {
            background: #e8e8e8;
            color: #000;
        }

        .toolbar-btn i {
            margin-right: 5px;
        }

        .toolbar-btn.active {
            background: var(--primary-color);
            color: white;
        }

        .editor-preview-container {
            display: flex;
            flex: 1;
            overflow: hidden;
        }

        .editor-container,
        .preview-container {
            flex: 1;
            padding: 15px;
            box-sizing: border-box;
            overflow-y: auto;
            height: calc(100vh - 150px);
        }

        .editor-container {
            border-right: 1px solid var(--border-color);
            display: flex;
            flex-direction: column;
        }

        textarea {
            width: 100%;
            flex: 1;
            border: 1px solid var(--border-color);
            border-radius: 4px;
            resize: none;
            outline: none;
            font-size: 15px;
            line-height: 1.5;
            font-family: 'Consolas', 'Courier New', monospace;
            padding: 10px;
            margin-top: 10px;
        }

        .preview-container {
            background-color: #f8f8f8;
        }

        h1 {
            margin-top: 0;
            color: var(--primary-color);
            font-size: 1.5em;
        }

        #preview {
            height: calc(100% - 40px);
            overflow-y: auto;
            padding: 10px;
            background: white;
            border-radius: 4px;
            border: 1px solid var(--border-color);
        }

        .header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 10px;
        }

        .action-btn {
            padding: 6px 12px;
            background: var(--primary-color);
            border: none;
            border-radius: 4px;
            cursor: pointer;
            color: white;
            font-weight: bold;
        }

        .action-btn:hover {
            background: var(--hover-color);
        }

        .action-btn i {
            margin-right: 5px;
        }

        .export-options {
            display: none;
            position: absolute;
            right: 10px;
            top: 40px;
            background: white;
            border: 1px solid var(--border-color);
            border-radius: 4px;
            padding: 5px;
            z-index: 100;
        }

        .import-options {
            display: none;
            position: absolute;
            right: 10px;
            top: 40px;
            background: white;
            border: 1px solid var(--border-color);
            border-radius: 4px;
            padding: 5px;
            z-index: 100;
        }

        .export-btn, .import-btn {
            display: block;
            width: 100%;
            padding: 5px 10px;
            text-align: left;
            background: none;
            border: none;
            cursor: pointer;
        }

        .export-btn:hover, .import-btn:hover {
            background-color: var(--toolbar-bg);
        }

        .has-export:hover .export-options {
            display: block;
        }

        .has-import:hover .import-options {
            display: block;
        }

        .file-input {
            display: none;
        }

        @media (max-width: 768px) {
            .editor-preview-container {
                flex-direction: column;
            }

            .editor-container,
            .preview-container {
                height: calc(50vh - 75px);
            }

            .editor-container {
                border-right: none;
                border-bottom: 1px solid var(--border-color);
            }

            .toolbar {
                overflow-x: auto;
                justify-content: flex-start;
            }
        }