Add font size adjustment menu and fix theme styling

Features:
• Added Font Size menu in View with increase/decrease/reset options
• Keyboard shortcuts: Ctrl+Shift+Plus/Minus/0 for font adjustment
• Font size persists between sessions using localStorage
• Font sizes adjustable from 10px to 24px

Theme Fixes:
• Fixed missing Monokai theme styles for tabs and editor
• Added complete tab styling for Solarized theme
• Added complete tab styling for GitHub theme
• All themes now have consistent tab bar appearance

Other Changes:
• Updated CLAUDE.md with v1.3.x features documentation
• Version bumped to 1.3.4

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

CLAUDE.md

@@ -0,0 +1,334 @@
+# PanConverter - Claude Development Guide
+
+## Project Overview
+
+**PanConverter** is a cross-platform Markdown editor and converter powered by Pandoc, built with Electron. It provides professional-grade editing capabilities with comprehensive export options.
+
+**Current Version**: v1.3.3  
+**Author**: Amit Haridas (amit.wh@gmail.com)  
+**License**: MIT  
+**Repository**: https://github.com/amitwh/pan-converter
+
+## Architecture & Technology Stack
+
+### Core Technologies
+- **Electron** - Cross-platform desktop application framework
+- **Pandoc** - Universal document converter (required dependency)
+- **marked** - Markdown parsing and rendering
+- **highlight.js** - Syntax highlighting
+- **XLSX** - Spreadsheet export functionality
+- **DOMPurify** - HTML sanitization
+
+### Application Structure
+```
+src/
+├── main.js        # Electron main process, menu system, IPC handlers
+├── renderer.js    # TabManager class, multi-file editing, event handling
+├── index.html     # Application layout with tabbed interface
+└── styles.css     # Comprehensive styling with multi-theme support
+
+assets/
+└── icon.png       # Application icon
+
+package.json       # Dependencies and build configuration
+CLAUDE.md          # Development documentation for AI assistants
+```
+
+## Development Commands
+
+### Prerequisites
+```bash
+# Install Node.js dependencies
+npm install
+
+# Install Pandoc (required for export functionality)
+# Ubuntu/Debian:
+sudo apt-get install pandoc
+
+# macOS:
+brew install pandoc
+
+# Windows: Download from https://pandoc.org/installing.html
+```
+
+### Running the Application
+```bash
+# Start development server
+npm start
+
+# Start with debugging
+npm start --enable-logging
+```
+
+### Building & Packaging
+
+```bash
+# Generate application icons
+npm run generate-icons
+
+# Build for current platform
+npm run build
+
+# Platform-specific builds
+npm run build:win      # Windows
+npm run build:mac      # macOS
+npm run build:linux    # Linux (AppImage, .deb, .snap)
+
+# Build for all platforms
+npm run dist:all
+```
+
+### Git Branch Management
+```bash
+# Switch to platform-specific branches
+git checkout linux    # Linux development
+git checkout macos     # macOS development  
+git checkout windows   # Windows development
+git checkout master    # Main development branch
+
+# Update all branches with latest changes
+git checkout master
+git push origin master
+git checkout linux && git merge master && git push origin linux
+git checkout macos && git merge master && git push origin macos
+git checkout windows && git merge master && git push origin windows
+```
+
+### Release Management
+```bash
+# Create and push release tag
+git tag v1.2.1 -m "Release message"
+git push origin v1.2.1
+
+# Create GitHub release with packages
+gh release create v1.2.1 --title "Title" --notes "Release notes" \
+  "dist/PanConverter-1.2.1.AppImage" \
+  "dist/pan-converter_1.2.1_amd64.deb" \
+  "dist/pan-converter_1.2.1_amd64.snap"
+```
+
+## Feature Implementation Guide
+
+### v1.3.x Tabbed Interface & Enhanced Features
+
+#### 🗂️ Tabbed Multi-File Support (v1.3.0)
+**TabManager Class** (`src/renderer.js`)
+- Complete tab management system for multiple files
+- Tab switching, creation, and closure
+- State preservation per tab (content, cursor position, scroll)
+- File path tracking for each tab
+- Keyboard shortcuts: `Ctrl/Cmd+T` (new tab), `Ctrl/Cmd+W` (close tab)
+
+#### 🎯 Enhanced PDF Export (v1.3.0)
+**Multi-Engine Fallback System** (`src/main.js:239-280`)
+- Primary: XeLaTeX with proper margins
+- Fallback 1: PDFLaTeX
+- Fallback 2: wkhtmltopdf
+- Automatic engine detection and switching
+
+#### 📁 File Association Support (v1.3.1)
+**OS Integration** (`src/main.js:452-498`, `package.json:50-65`)
+- Double-click .md files to open in PanConverter
+- Command-line argument handling
+- Pending file queue for startup loading
+
+#### 🎨 Typography & Spacing (v1.3.2-1.3.3)
+**Preview Enhancement** (`src/styles.css`)
+- Restored ideal text spacing from v1.0
+- Font sizes increased to 15px for better readability
+- Comprehensive selector coverage for legacy and new containers
+- Theme-aware typography for all content types
+
+### v1.2.1 Comprehensive Editor Enhancements
+
+#### ✨ Advanced Editor Features
+
+**Find & Replace System** (`src/renderer.js:200-350`)
+- Dialog-based interface with match highlighting
+- Forward/backward navigation through matches
+- Replace single or replace all functionality
+- Real-time match counting and status display
+- Escape key closes dialog
+
+**Line Numbers** (`src/renderer.js:450-500`, `src/styles.css:517-598`)
+- Toggle-able line numbers with toolbar button
+- Synchronized scrolling with editor content
+- Theme-aware styling for all supported themes
+- Dynamic line number generation based on content
+
+**Undo/Redo System** (`src/renderer.js:100-150`)
+- Stack-based state management for editor history
+- Keyboard shortcuts: `Ctrl/Cmd+Z` (undo), `Ctrl/Cmd+Shift+Z` (redo)
+- Intelligent state saving on text changes
+- Memory-efficient history management
+
+**Smart Auto-Indentation** (`src/renderer.js:350-400`)
+- Automatic list continuation on Enter key
+- Proper indentation handling for nested lists
+- Support for ordered and unordered lists
+- Intelligent whitespace management
+
+**Enhanced Keyboard Shortcuts** (`src/renderer.js:400-450`)
+- `Tab`/`Shift+Tab` for line indentation/outdentation
+- `Enter` for auto-continuing lists
+- `Ctrl/Cmd+F` for find & replace dialog
+- `Escape` for closing dialogs
+
+**Word/Character Count** (`src/renderer.js:500-530`)
+- Live counting displayed in status bar
+- Updates automatically as content changes
+- Word and character statistics
+
+#### 📤 Export & Conversion Features
+
+**PowerPoint Export** (`src/main.js:330-350`)
+- Convert markdown to PPTX presentations
+- Automatic slide-level formatting (`--slide-level=2`)
+- Smart presentation structure handling
+
+**Spreadsheet Export** (`src/main.js:370-457`)
+- Export markdown tables to Excel (XLSX/XLS) and ODS formats
+- Multi-table support with separate worksheets
+- Automatic table detection and parsing
+- Error handling for files without tables
+
+**Document Import** (`src/main.js:280-315`)
+- Import DOCX, ODT, RTF, HTML, PDF, PPTX, ODP files
+- Automatic conversion to markdown format
+- File dialog with appropriate filters
+- Success notifications and error handling
+
+**Table Creation Helper** (`src/renderer.js:600-650`)
+- Built-in table generator with row/column specification
+- Automatic markdown table formatting
+- Proper header separation and alignment
+
+#### 🎨 Interface & Theming
+
+**Multi-Theme Support** (`src/styles.css:214-598`)
+- Light, Dark, Solarized, Monokai, GitHub themes
+- Complete theming for all UI components
+- Theme-aware styling for new features (find dialog, line numbers)
+- Persistent theme selection with local storage
+
+**Enhanced UI Components** (`src/index.html:94-108`)
+- Find & replace dialog with modern styling
+- Toolbar buttons for all new features
+- Status bar with live statistics
+- Responsive layout with proper spacing
+
+## File Structure & Key Components
+
+### Main Process (`src/main.js`)
+- **Menu System**: Comprehensive menu with file operations, editing, conversion, view options
+- **IPC Handlers**: Communication between main and renderer processes
+- **File Operations**: Open, save, import/export functionality
+- **Theme Management**: Persistent theme storage and application
+- **Spreadsheet Export**: Table extraction and XLSX generation
+- **About Dialog**: Application information and feature list
+
+### Renderer Process (`src/renderer.js`)
+- **Editor Initialization**: CodeMirror-like functionality with custom implementation
+- **Find & Replace Engine**: Search algorithms with regex support
+- **Undo/Redo Manager**: History stack management
+- **Auto-indentation Logic**: Smart list continuation
+- **Live Preview**: Real-time markdown rendering with DOMPurify
+- **Event Handling**: Keyboard shortcuts and UI interactions
+- **Statistics Tracking**: Word/character counting
+
+### Styling (`src/styles.css`)
+- **Base Styles**: Application layout and typography
+- **Component Styles**: Toolbar, editor, preview, dialogs
+- **Theme Implementations**: Complete styling for all themes
+- **Responsive Design**: Flexible layouts and proper spacing
+- **Animation Support**: Smooth transitions and hover effects
+
+### HTML Structure (`src/index.html`)
+- **Toolbar**: Feature buttons with SVG icons
+- **Find Dialog**: Search and replace interface
+- **Editor Container**: Line numbers and text editor
+- **Preview Pane**: Rendered markdown display
+- **Status Bar**: Statistics and application status
+
+## Testing & Quality Assurance
+
+### Manual Testing Checklist
+- [ ] All keyboard shortcuts work correctly
+- [ ] Find & replace functions properly with edge cases
+- [ ] Line numbers sync correctly with content
+- [ ] Undo/redo preserves cursor position
+- [ ] Auto-indentation works with various list types
+- [ ] All themes render correctly for new components
+- [ ] Export functions work with various document formats
+- [ ] Table creation and export functionality
+- [ ] Cross-platform compatibility
+
+### Known Issues & Limitations
+- AppImage may require `--no-sandbox` flag on some Linux systems
+- Large files (>1MB) may cause performance issues
+- Windows/Mac builds require platform-specific environments
+- Pandoc must be installed separately for export functionality
+
+## Deployment & Distribution
+
+### Release Packages
+- **Linux AppImage**: Universal Linux package (self-contained)
+- **Debian Package**: `.deb` for Ubuntu/Debian systems
+- **Snap Package**: Universal Linux package via Snap Store
+- **Future**: Windows `.exe` and macOS `.dmg` packages
+
+### Release Process
+1. Update version in `package.json`, `src/main.js`, and `README.md`
+2. Commit changes and push to all platform branches
+3. Build platform-specific packages
+4. Create Git tag and GitHub release
+5. Upload packages to GitHub release
+6. Update documentation and announce release
+
+## Contributing Guidelines
+
+### Code Style
+- Use consistent indentation (2 spaces)
+- Follow JavaScript ES6+ standards
+- Comment complex functionality
+- Maintain separation between main and renderer processes
+- Use descriptive variable and function names
+
+### Adding New Features
+1. Plan feature implementation and UI integration
+2. Update relevant files (main.js, renderer.js, styles.css)
+3. Test across all supported themes
+4. Update documentation and README
+5. Test on multiple platforms if possible
+6. Submit pull request with detailed description
+
+### Bug Reporting
+- Include steps to reproduce
+- Specify platform and version information
+- Attach relevant screenshots or error logs
+- Check existing issues before creating new ones
+
+## Future Roadmap
+
+### Planned Features
+- [ ] Collaborative editing capabilities
+- [ ] Plugin system for extensions
+- [ ] Advanced markdown extensions (math, diagrams)
+- [ ] Cloud synchronization options
+- [ ] Mobile companion app
+- [ ] Advanced export templates
+- [ ] Spell check and grammar checking
+- [ ] Version control integration
+
+### Technical Improvements
+- [ ] Performance optimization for large files
+- [ ] Memory usage optimization
+- [ ] Startup time improvements
+- [ ] Better error handling and user feedback
+- [ ] Automated testing suite
+- [ ] Continuous integration/deployment
+
+---
+
+**Last Updated**: September 1, 2025  
+**Claude Assistant**: Development completed for v1.3.3 with tabbed interface, enhanced PDF export, file associations, and improved typography

README.latex

@@ -0,0 +1,378 @@
+\hypertarget{panconverter}{%
+\section{PanConverter}\label{panconverter}}
+
+A cross-platform Markdown editor and converter powered by Pandoc.
+
+\begin{figure}
+\centering
+\includegraphics{assets/icon.png}
+\caption{PanConverter}
+\end{figure}
+
+\hypertarget{features}{%
+\subsection{Features}\label{features}}
+
+\hypertarget{advanced-markdown-editor}{%
+\subsubsection{✨ Advanced Markdown
+Editor}\label{advanced-markdown-editor}}
+
+\begin{itemize}
+\tightlist
+\item
+  🗂️ \textbf{Tabbed Interface} - Work with multiple files simultaneously
+  in separate tabs
+\item
+  📝 \textbf{Rich Text Editor} - Full-featured editor with syntax
+  highlighting and comprehensive toolbar
+\item
+  🔍 \textbf{Find \& Replace} - Powerful search and replace with match
+  highlighting and navigation
+\item
+  🔢 \textbf{Line Numbers} - Toggle line numbers for easier code editing
+  and navigation
+\item
+  ↩️ \textbf{Smart Auto-Indentation} - Automatic list continuation and
+  intelligent indentation
+\item
+  ⏪ \textbf{Undo/Redo} - Full undo/redo support with keyboard shortcuts
+\item
+  ⌨️ \textbf{Advanced Shortcuts} - Tab indentation, line selection, and
+  smart text formatting
+\item
+  📂 \textbf{File Association Support} - Open markdown files directly
+  from file manager
+\end{itemize}
+
+\hypertarget{themes-interface}{%
+\subsubsection{🎨 Themes \& Interface}\label{themes-interface}}
+
+\begin{itemize}
+\tightlist
+\item
+  👁️ \textbf{Live Preview} - See your markdown rendered in real-time
+  with synchronized scrolling
+\item
+  🎨 \textbf{Multiple Themes} - Choose from Light, Dark, Solarized,
+  Monokai, or GitHub themes
+\item
+  💾 \textbf{Auto-Save} - Never lose your work with automatic saving
+  every 30 seconds
+\end{itemize}
+
+\hypertarget{export-conversion}{%
+\subsubsection{📤 Export \& Conversion}\label{export-conversion}}
+
+\begin{itemize}
+\tightlist
+\item
+  📄 \textbf{Enhanced PDF Export} - Robust PDF generation with multiple
+  LaTeX engine fallbacks (XeLaTeX, PDFLaTeX, wkhtmltopdf)
+\item
+  📄 \textbf{Document Export} - Convert to HTML, DOCX, LaTeX, RTF, ODT,
+  EPUB, PowerPoint (PPTX), and OpenDocument Presentation (ODP)
+\item
+  📊 \textbf{Spreadsheet Export} - Export markdown tables to Excel
+  (XLSX/XLS) and OpenDocument Spreadsheet (ODS) formats
+\item
+  📥 \textbf{Document Import} - Import DOCX, ODT, RTF, HTML, PDF, and
+  presentation files to markdown
+\item
+  📋 \textbf{Table Creation Helper} - Built-in table generator for easy
+  markdown table creation
+\end{itemize}
+
+\hypertarget{platform-support}{%
+\subsubsection{🖥️ Platform Support}\label{platform-support}}
+
+\begin{itemize}
+\tightlist
+\item
+  \textbf{Cross-Platform} - Works seamlessly on Windows, macOS, and
+  Linux
+\end{itemize}
+
+\hypertarget{installation}{%
+\subsection{Installation}\label{installation}}
+
+\hypertarget{prerequisites}{%
+\subsubsection{Prerequisites}\label{prerequisites}}
+
+\begin{itemize}
+\tightlist
+\item
+  \href{https://pandoc.org/installing.html}{Pandoc} must be installed
+  for export functionality
+
+  \begin{itemize}
+  \tightlist
+  \item
+    \textbf{Ubuntu/Debian}: \texttt{sudo\ apt-get\ install\ pandoc}
+  \item
+    \textbf{macOS}: \texttt{brew\ install\ pandoc}
+  \item
+    \textbf{Windows}: Download installer from Pandoc website
+  \end{itemize}
+\end{itemize}
+
+\hypertarget{pdf-export-requirements}{%
+\subsubsection{PDF Export Requirements}\label{pdf-export-requirements}}
+
+For optimal PDF export, install a LaTeX engine (recommended): -
+\textbf{Ubuntu/Debian}:
+\texttt{sudo\ apt-get\ install\ texlive-xetex\ texlive-latex-base} -
+\textbf{macOS}: \texttt{brew\ install\ -\/-cask\ mactex} -
+\textbf{Windows}: Install MiKTeX or TeX Live - \textbf{Alternative}:
+\texttt{sudo\ apt-get\ install\ wkhtmltopdf} (fallback option)
+
+\hypertarget{download}{%
+\subsubsection{Download}\label{download}}
+
+Download the latest release for your platform from the
+\href{https://github.com/amitwh/pan-converter/releases}{Releases} page.
+
+\hypertarget{linux}{%
+\paragraph{Linux}\label{linux}}
+
+\begin{itemize}
+\tightlist
+\item
+  \textbf{AppImage}: \texttt{PanConverter-1.3.1.AppImage} (universal,
+  may require \texttt{-\/-no-sandbox} flag)
+\item
+  \textbf{Debian Package}: \texttt{pan-converter\_1.3.1\_amd64.deb}
+\item
+  \textbf{Snap Package}: \texttt{pan-converter\_1.3.1\_amd64.snap}
+\end{itemize}
+
+\hypertarget{install-from-source}{%
+\subsubsection{Install from Source}\label{install-from-source}}
+
+\begin{Shaded}
+\begin{Highlighting}[]
+\FunctionTok{git}\NormalTok{ clone https://github.com/amitwh/pan{-}converter.git}
+\BuiltInTok{cd}\NormalTok{ pan{-}converter}
+\ExtensionTok{npm}\NormalTok{ install}
+\ExtensionTok{npm}\NormalTok{ start}
+\end{Highlighting}
+\end{Shaded}
+
+\hypertarget{usage}{%
+\subsection{Usage}\label{usage}}
+
+\hypertarget{basic-workflow}{%
+\subsubsection{Basic Workflow}\label{basic-workflow}}
+
+\begin{enumerate}
+\def\labelenumi{\arabic{enumi}.}
+\tightlist
+\item
+  \textbf{Write} - Use the editor to write your Markdown content
+\item
+  \textbf{Preview} - Toggle the preview pane to see rendered output
+\item
+  \textbf{Theme} - Choose your preferred theme from the View menu
+\item
+  \textbf{Export} - Export your document to various formats
+\end{enumerate}
+
+\hypertarget{export-options}{%
+\subsubsection{Export Options}\label{export-options}}
+
+\begin{itemize}
+\tightlist
+\item
+  \textbf{Documents}: HTML, PDF, DOCX, LaTeX, RTF, ODT, EPUB
+\item
+  \textbf{Presentations}: PowerPoint (PPTX), OpenDocument Presentation
+  (ODP)
+\item
+  \textbf{Spreadsheets}: Excel (XLSX/XLS), OpenDocument Spreadsheet
+  (ODS)
+\end{itemize}
+
+\hypertarget{import-conversion}{%
+\subsubsection{Import \& Conversion}\label{import-conversion}}
+
+\begin{itemize}
+\tightlist
+\item
+  \textbf{Import Documents}: Convert DOCX, ODT, RTF, HTML, PDF, and
+  presentation files to Markdown
+\item
+  \textbf{Cross-Format Conversion}: Convert current file between
+  multiple formats
+\item
+  \textbf{Smart Presentation Handling}: Automatic slide-level formatting
+  for PPTX/ODP exports
+\end{itemize}
+
+\hypertarget{table-creation}{%
+\subsubsection{Table Creation}\label{table-creation}}
+
+\begin{itemize}
+\tightlist
+\item
+  Click the table button in the toolbar
+\item
+  Specify number of rows and columns
+\item
+  Automatically generates properly formatted Markdown tables
+\end{itemize}
+
+\hypertarget{keyboard-shortcuts}{%
+\subsection{Keyboard Shortcuts}\label{keyboard-shortcuts}}
+
+\hypertarget{file-operations}{%
+\subsubsection{File Operations}\label{file-operations}}
+
+\begin{itemize}
+\tightlist
+\item
+  \texttt{Ctrl/Cmd\ +\ N} - New file/tab
+\item
+  \texttt{Ctrl/Cmd\ +\ T} - New tab
+\item
+  \texttt{Ctrl/Cmd\ +\ W} - Close current tab
+\item
+  \texttt{Ctrl/Cmd\ +\ Tab} - Switch to next tab
+\item
+  \texttt{Ctrl/Cmd\ +\ O} - Open file
+\item
+  \texttt{Ctrl/Cmd\ +\ S} - Save file
+\item
+  \texttt{Ctrl/Cmd\ +\ Shift\ +\ S} - Save as
+\item
+  \texttt{Ctrl/Cmd\ +\ I} - Import document
+\end{itemize}
+
+\hypertarget{editor-features}{%
+\subsubsection{Editor Features}\label{editor-features}}
+
+\begin{itemize}
+\tightlist
+\item
+  \texttt{Ctrl/Cmd\ +\ F} - Find \& Replace
+\item
+  \texttt{Ctrl/Cmd\ +\ Z} - Undo
+\item
+  \texttt{Ctrl/Cmd\ +\ Shift\ +\ Z} - Redo
+\item
+  \texttt{Tab} - Indent lines or insert 4 spaces
+\item
+  \texttt{Shift\ +\ Tab} - Outdent selected lines
+\item
+  \texttt{Enter} - Auto-continue lists with proper indentation
+\end{itemize}
+
+\hypertarget{view-navigation}{%
+\subsubsection{View \& Navigation}\label{view-navigation}}
+
+\begin{itemize}
+\tightlist
+\item
+  \texttt{Ctrl/Cmd\ +\ P} - Toggle preview
+\item
+  \texttt{Ctrl/Cmd\ +\ Enter} - Toggle preview (alternative)
+\item
+  \texttt{Escape} - Close find dialog
+\end{itemize}
+
+\hypertarget{building}{%
+\subsection{Building}\label{building}}
+
+\begin{Shaded}
+\begin{Highlighting}[]
+\CommentTok{\# Install dependencies}
+\ExtensionTok{npm}\NormalTok{ install}
+
+\CommentTok{\# Generate icons}
+\ExtensionTok{npm}\NormalTok{ run generate{-}icons}
+
+\CommentTok{\# Build for current platform}
+\ExtensionTok{npm}\NormalTok{ run build}
+
+\CommentTok{\# Build for specific platform}
+\ExtensionTok{npm}\NormalTok{ run build:win    }\CommentTok{\# Windows}
+\ExtensionTok{npm}\NormalTok{ run build:mac    }\CommentTok{\# macOS  }
+\ExtensionTok{npm}\NormalTok{ run build:linux  }\CommentTok{\# Linux (generates .deb, .AppImage, and .snap)}
+
+\CommentTok{\# Build for all platforms}
+\ExtensionTok{npm}\NormalTok{ run dist:all}
+\end{Highlighting}
+\end{Shaded}
+
+\hypertarget{version-history}{%
+\subsection{Version History}\label{version-history}}
+
+\begin{itemize}
+\tightlist
+\item
+  \textbf{v1.3.1} - Bug fixes: Fixed file associations for
+  double-clicking .md files, corrected 50/50 layout alignment for
+  editor/preview panes
+\item
+  \textbf{v1.3.0} - Major update: Tabbed interface for multiple files,
+  enhanced PDF export with LaTeX engines, fixed file associations,
+  removed redundant converter menu, improved UI architecture
+\item
+  \textbf{v1.2.1} - Comprehensive editor enhancements: Find \& Replace,
+  Line Numbers, Undo/Redo, Auto-indentation, PowerPoint export, document
+  conversion menu, table creation helper, spreadsheet export
+\item
+  \textbf{v1.1.0} - Added Excel/ODS spreadsheet export, updated author
+  information, renamed to PanConverter
+\item
+  \textbf{v1.0.0} - Initial release with basic markdown editing, themes,
+  and Pandoc export
+\end{itemize}
+
+\hypertarget{known-issues}{%
+\subsection{Known Issues}\label{known-issues}}
+
+\begin{itemize}
+\tightlist
+\item
+  AppImage may require \texttt{-\/-no-sandbox} flag on some Linux
+  systems
+\item
+  Windows/Mac builds require platform-specific build environments
+\item
+  Large files may cause performance issues
+\end{itemize}
+
+\hypertarget{contributing}{%
+\subsection{Contributing}\label{contributing}}
+
+Contributions are welcome! Please feel free to submit a Pull Request to
+the \href{https://github.com/amitwh/pan-converter}{GitHub repository}.
+
+\hypertarget{license}{%
+\subsection{License}\label{license}}
+
+MIT License - see LICENSE file for details.
+
+\hypertarget{author}{%
+\subsection{Author}\label{author}}
+
+\textbf{Amit Haridas} -
+\href{mailto:amit.wh@gmail.com}{\nolinkurl{amit.wh@gmail.com}}
+
+\hypertarget{acknowledgments}{%
+\subsection{Acknowledgments}\label{acknowledgments}}
+
+\begin{itemize}
+\tightlist
+\item
+  Built with \href{https://www.electronjs.org/}{Electron}
+\item
+  Markdown parsing by \href{https://marked.js.org/}{marked}
+\item
+  Export functionality powered by \href{https://pandoc.org/}{Pandoc}
+\item
+  Syntax highlighting by \href{https://highlightjs.org/}{highlight.js}
+\item
+  Spreadsheet export by \href{https://www.npmjs.com/package/xlsx}{XLSX}
+\item
+  HTML sanitization by
+  \href{https://www.npmjs.com/package/dompurify}{DOMPurify}
+\end{itemize}

README.md

@@ -7,12 +7,14 @@ A cross-platform Markdown editor and converter powered by Pandoc.
 ## Features
 
 ### ✨ Advanced Markdown Editor
+- 🗂️ **Tabbed Interface** - Work with multiple files simultaneously in separate tabs
 - 📝 **Rich Text Editor** - Full-featured editor with syntax highlighting and comprehensive toolbar
 - 🔍 **Find & Replace** - Powerful search and replace with match highlighting and navigation
 - 🔢 **Line Numbers** - Toggle line numbers for easier code editing and navigation
 - ↩️ **Smart Auto-Indentation** - Automatic list continuation and intelligent indentation
 - ⏪ **Undo/Redo** - Full undo/redo support with keyboard shortcuts
 - ⌨️ **Advanced Shortcuts** - Tab indentation, line selection, and smart text formatting
+- 📂 **File Association Support** - Open markdown files directly from file manager
 
 ### 🎨 Themes & Interface
 - 👁️ **Live Preview** - See your markdown rendered in real-time with synchronized scrolling
@@ -20,9 +22,10 @@ A cross-platform Markdown editor and converter powered by Pandoc.
 - 💾 **Auto-Save** - Never lose your work with automatic saving every 30 seconds
 
 ### 📤 Export & Conversion
-- 📄 **Document Export** - Convert to HTML, PDF, DOCX, LaTeX, RTF, ODT, EPUB, PowerPoint (PPTX), and OpenDocument Presentation (ODP)
+- 📄 **Enhanced PDF Export** - Robust PDF generation with multiple LaTeX engine fallbacks (XeLaTeX, PDFLaTeX, wkhtmltopdf)
+- 📄 **Document Export** - Convert to HTML, DOCX, LaTeX, RTF, ODT, EPUB, PowerPoint (PPTX), and OpenDocument Presentation (ODP)
 - 📊 **Spreadsheet Export** - Export markdown tables to Excel (XLSX/XLS) and OpenDocument Spreadsheet (ODS) formats
-- 📥 **Document Import & Conversion** - Import various document formats and convert between formats via Pandoc
+- 📥 **Document Import** - Import DOCX, ODT, RTF, HTML, PDF, and presentation files to markdown
 - 📋 **Table Creation Helper** - Built-in table generator for easy markdown table creation
 
 ### 🖥️ Platform Support
@@ -36,13 +39,20 @@ A cross-platform Markdown editor and converter powered by Pandoc.
   - **macOS**: `brew install pandoc`
   - **Windows**: Download installer from Pandoc website
 
+### PDF Export Requirements
+For optimal PDF export, install a LaTeX engine (recommended):
+- **Ubuntu/Debian**: `sudo apt-get install texlive-xetex texlive-latex-base`
+- **macOS**: `brew install --cask mactex`
+- **Windows**: Install MiKTeX or TeX Live
+- **Alternative**: `sudo apt-get install wkhtmltopdf` (fallback option)
+
 ### Download
 Download the latest release for your platform from the [Releases](https://github.com/amitwh/pan-converter/releases) page.
 
 #### Linux
-- **AppImage**: `PanConverter-1.2.0.AppImage` (universal, may require `--no-sandbox` flag)
-- **Debian Package**: `pan-converter_1.2.0_amd64.deb`
-- **Snap Package**: `pan-converter_1.2.0_amd64.snap`
+- **AppImage**: `PanConverter-1.3.1.AppImage` (universal, may require `--no-sandbox` flag)
+- **Debian Package**: `pan-converter_1.3.1_amd64.deb`
+- **Snap Package**: `pan-converter_1.3.1_amd64.snap`
 
 ### Install from Source
 ```bash
@@ -78,7 +88,10 @@ npm start
 ## Keyboard Shortcuts
 
 ### File Operations
-- `Ctrl/Cmd + N` - New file
+- `Ctrl/Cmd + N` - New file/tab
+- `Ctrl/Cmd + T` - New tab
+- `Ctrl/Cmd + W` - Close current tab
+- `Ctrl/Cmd + Tab` - Switch to next tab
 - `Ctrl/Cmd + O` - Open file
 - `Ctrl/Cmd + S` - Save file
 - `Ctrl/Cmd + Shift + S` - Save as
@@ -120,7 +133,9 @@ npm run dist:all
 
 ## Version History
 
-- **v1.2.0** - Major editor enhancements: Find & Replace, Line Numbers, Undo/Redo, Auto-indentation, PowerPoint export, document conversion menu, table creation helper, spreadsheet export
+- **v1.3.1** - Bug fixes: Fixed file associations for double-clicking .md files, corrected 50/50 layout alignment for editor/preview panes
+- **v1.3.0** - Major update: Tabbed interface for multiple files, enhanced PDF export with LaTeX engines, fixed file associations, removed redundant converter menu, improved UI architecture
+- **v1.2.1** - Comprehensive editor enhancements: Find & Replace, Line Numbers, Undo/Redo, Auto-indentation, PowerPoint export, document conversion menu, table creation helper, spreadsheet export
 - **v1.1.0** - Added Excel/ODS spreadsheet export, updated author information, renamed to PanConverter
 - **v1.0.0** - Initial release with basic markdown editing, themes, and Pandoc export
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "pan-converter",
-  "version": "1.2.0",
+  "version": "1.3.4",
   "description": "Cross-platform Markdown editor and converter using Pandoc",
   "main": "src/main.js",
   "scripts": {
@@ -47,6 +47,22 @@
       "node_modules/**/*",
       "package.json"
     ],
+    "fileAssociations": [
+      {
+        "ext": "md",
+        "name": "Markdown Document",
+        "description": "Markdown Document",
+        "mimeType": "text/markdown",
+        "role": "Editor"
+      },
+      {
+        "ext": "markdown",
+        "name": "Markdown Document",
+        "description": "Markdown Document", 
+        "mimeType": "text/markdown",
+        "role": "Editor"
+      }
+    ],
     "mac": {
       "category": "public.app-category.productivity",
       "icon": "assets/icon.icns"

src/index.html

@@ -10,6 +10,13 @@
 </head>
 <body>
     <div class="container">
+        <div class="tab-bar" id="tab-bar">
+            <div class="tab active" data-tab-id="1">
+                <span class="tab-title">Untitled</span>
+                <button class="tab-close" title="Close tab">×</button>
+            </div>
+            <button class="new-tab-button" id="new-tab-btn" title="New tab">+</button>
+        </div>
         <div class="toolbar">
             <button id="btn-bold" title="Bold">
                 <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
@@ -108,14 +115,16 @@
         </div>
         
         <div class="editor-container">
-            <div id="editor-pane" class="pane">
-                <div class="editor-wrapper">
-                    <div id="line-numbers" class="line-numbers hidden"></div>
-                    <textarea id="editor"></textarea>
+            <div class="tab-content active" id="tab-content-1" data-tab-id="1">
+                <div id="editor-pane-1" class="pane">
+                    <div class="editor-wrapper">
+                        <div id="line-numbers-1" class="line-numbers hidden"></div>
+                        <textarea id="editor-1" class="editor-textarea"></textarea>
+                    </div>
+                </div>
+                <div id="preview-pane-1" class="pane">
+                    <div id="preview-1" class="preview-content"></div>
                 </div>
-            </div>
-            <div id="preview-pane" class="pane">
-                <div id="preview"></div>
             </div>
         </div>
         

src/main.js

@@ -28,7 +28,7 @@ const store = {
 };
 
 let mainWindow;
-let currentFile = null;
+let currentFile = null; // This will now represent the active tab's file
 
 function createWindow() {
   mainWindow = new BrowserWindow({
@@ -48,6 +48,14 @@ function createWindow() {
   mainWindow.on('closed', () => {
     mainWindow = null;
   });
+
+  // Handle pending file from file association
+  if (app.pendingFile) {
+    mainWindow.webContents.once('dom-ready', () => {
+      openFileFromPath(app.pendingFile);
+      app.pendingFile = null;
+    });
+  }
 }
 
 function createMenu() {
@@ -76,6 +84,11 @@ function createMenu() {
           click: saveAsFile
         },
         { type: 'separator' },
+        {
+          label: 'Import Document...',
+          accelerator: 'CmdOrCtrl+I',
+          click: importDocument
+        },
         {
           label: 'Export',
           submenu: [
@@ -121,32 +134,6 @@ function createMenu() {
         }
       ]
     },
-    {
-      label: 'Convert',
-      submenu: [
-        {
-          label: 'Import Document...',
-          accelerator: 'CmdOrCtrl+I',
-          click: importDocument
-        },
-        { type: 'separator' },
-        {
-          label: 'Convert Current File',
-          submenu: [
-            { label: 'To Markdown', click: () => convertToFormat('md') },
-            { label: 'To HTML', click: () => convertToFormat('html') },
-            { label: 'To PDF', click: () => convertToFormat('pdf') },
-            { label: 'To DOCX', click: () => convertToFormat('docx') },
-            { label: 'To LaTeX', click: () => convertToFormat('latex') },
-            { label: 'To RTF', click: () => convertToFormat('rtf') },
-            { label: 'To ODT', click: () => convertToFormat('odt') },
-            { label: 'To EPUB', click: () => convertToFormat('epub') },
-            { label: 'To PPTX', click: () => convertToFormat('pptx') },
-            { label: 'To ODP', click: () => convertToFormat('odp') }
-          ]
-        }
-      ]
-    },
     {
       label: 'View',
       submenu: [
@@ -166,6 +153,27 @@ function createMenu() {
           ]
         },
         { type: 'separator' },
+        {
+          label: 'Font Size',
+          submenu: [
+            { 
+              label: 'Increase Font Size', 
+              accelerator: 'CmdOrCtrl+Shift+Plus',
+              click: () => mainWindow.webContents.send('adjust-font-size', 'increase')
+            },
+            { 
+              label: 'Decrease Font Size', 
+              accelerator: 'CmdOrCtrl+Shift+-',
+              click: () => mainWindow.webContents.send('adjust-font-size', 'decrease')
+            },
+            { 
+              label: 'Reset Font Size',
+              accelerator: 'CmdOrCtrl+Shift+0',
+              click: () => mainWindow.webContents.send('adjust-font-size', 'reset')
+            }
+          ]
+        },
+        { type: 'separator' },
         { label: 'Reload', accelerator: 'CmdOrCtrl+R', role: 'reload' },
         { label: 'Toggle DevTools', accelerator: 'F12', role: 'toggleDevTools' },
         { type: 'separator' },
@@ -184,7 +192,7 @@ function createMenu() {
               type: 'info',
               title: 'About PanConverter',
               message: 'PanConverter',
-              detail: 'A cross-platform Markdown editor and converter using Pandoc.\n\nVersion: 1.2.0\nAuthor: Amit Haridas\nEmail: amit.wh@gmail.com\nLicense: MIT\n\nFeatures:\n• Advanced markdown editing with live preview\n• Find & replace with match highlighting\n• Line numbers and auto-indentation\n• Export to multiple formats via Pandoc\n• PowerPoint & presentation export\n• Export tables to Excel/ODS spreadsheets\n• Document import & conversion\n• Table creation helper\n• Multiple themes support\n• Undo/redo functionality',
+              detail: 'A cross-platform Markdown editor and converter using Pandoc.\n\nVersion: 1.3.4\nAuthor: Amit Haridas\nEmail: amit.wh@gmail.com\nLicense: MIT\n\nFeatures:\n• Tabbed interface for multiple files\n• Advanced markdown editing with live preview\n• Enhanced PDF export with LaTeX engines\n• File association support for .md files\n• Improved preview typography and spacing\n• Adjustable font sizes via menu (Ctrl+Shift+Plus/Minus)\n• Complete theme support including Monokai fixes\n• Find & replace with match highlighting\n• Line numbers and auto-indentation\n• Export to multiple formats via Pandoc\n• PowerPoint & presentation export\n• Export tables to Excel/ODS spreadsheets\n• Document import & conversion\n• Table creation helper\n• Multiple themes support\n• Undo/redo functionality',
               buttons: ['OK']
             });
           }
@@ -246,23 +254,62 @@ function exportFile(format) {
   });
 
   if (outputFile) {
-    const pandocCmd = `pandoc "${currentFile}" -o "${outputFile}"`;
+    let pandocCmd = `pandoc "${currentFile}" -o "${outputFile}"`;
     
-    exec(pandocCmd, (error, stdout, stderr) => {
-      if (error) {
-        dialog.showErrorBox('Export Error', `Failed to export: ${error.message}\n\nMake sure Pandoc is installed.`);
-      } else {
-        dialog.showMessageBox(mainWindow, {
-          type: 'info',
-          title: 'Export Complete',
-          message: `File exported successfully to ${outputFile}`,
-          buttons: ['OK']
-        });
-      }
-    });
+    // Add specific options for PDF export to ensure proper generation
+    if (format === 'pdf') {
+      pandocCmd = `pandoc "${currentFile}" --pdf-engine=xelatex -V geometry:margin=1in -o "${outputFile}"`;
+      // Try with different PDF engines if xelatex fails
+      exec(pandocCmd, (error, stdout, stderr) => {
+        if (error) {
+          // Fallback to pdflatex
+          const fallbackCmd = `pandoc "${currentFile}" --pdf-engine=pdflatex -V geometry:margin=1in -o "${outputFile}"`;
+          exec(fallbackCmd, (fallbackError, fallbackStdout, fallbackStderr) => {
+            if (fallbackError) {
+              // Final fallback to wkhtmltopdf
+              const htmlToPdfCmd = `pandoc "${currentFile}" -t html5 | wkhtmltopdf - "${outputFile}"`;
+              exec(htmlToPdfCmd, (finalError) => {
+                if (finalError) {
+                  dialog.showErrorBox('PDF Export Error', 
+                    `Failed to export PDF. Please ensure you have one of the following installed:\n` +
+                    `• XeLaTeX (recommended): sudo apt-get install texlive-xetex\n` +
+                    `• PDFLaTeX: sudo apt-get install texlive-latex-base\n` +
+                    `• wkhtmltopdf: sudo apt-get install wkhtmltopdf\n\n` +
+                    `Error: ${finalError.message}`
+                  );
+                } else {
+                  showExportSuccess(outputFile);
+                }
+              });
+            } else {
+              showExportSuccess(outputFile);
+            }
+          });
+        } else {
+          showExportSuccess(outputFile);
+        }
+      });
+    } else {
+      exec(pandocCmd, (error, stdout, stderr) => {
+        if (error) {
+          dialog.showErrorBox('Export Error', `Failed to export: ${error.message}\n\nMake sure Pandoc is installed.`);
+        } else {
+          showExportSuccess(outputFile);
+        }
+      });
+    }
   }
 }
 
+function showExportSuccess(outputFile) {
+  dialog.showMessageBox(mainWindow, {
+    type: 'info',
+    title: 'Export Complete',
+    message: `File exported successfully to ${outputFile}`,
+    buttons: ['OK']
+  });
+}
+
 function exportSpreadsheet(format) {
   if (!currentFile) {
     dialog.showErrorBox('Error', 'Please save the file first');
@@ -310,40 +357,6 @@ function importDocument() {
   }
 }
 
-function convertToFormat(format) {
-  if (!currentFile) {
-    dialog.showErrorBox('Error', 'Please save or open a file first');
-    return;
-  }
-
-  const outputFile = dialog.showSaveDialogSync(mainWindow, {
-    defaultPath: currentFile.replace(/\.[^/.]+$/, `.${format}`),
-    filters: [
-      { name: format.toUpperCase(), extensions: [format] }
-    ]
-  });
-
-  if (outputFile) {
-    // For presentations, add slide level for better conversion
-    let pandocCmd = `pandoc "${currentFile}" -o "${outputFile}"`;
-    if (format === 'pptx' || format === 'odp') {
-      pandocCmd = `pandoc "${currentFile}" --slide-level=2 -o "${outputFile}"`;
-    }
-    
-    exec(pandocCmd, (error, stdout, stderr) => {
-      if (error) {
-        dialog.showErrorBox('Conversion Error', `Failed to convert: ${error.message}\n\nMake sure Pandoc is installed.`);
-      } else {
-        dialog.showMessageBox(mainWindow, {
-          type: 'info',
-          title: 'Conversion Complete',
-          message: `File converted successfully to ${outputFile}`,
-          buttons: ['OK']
-        });
-      }
-    });
-  }
-}
 
 function setTheme(theme) {
   store.set('theme', theme);
@@ -369,6 +382,11 @@ ipcMain.on('get-theme', (event) => {
   event.reply('theme-changed', theme);
 });
 
+// Handle tab file tracking for exports
+ipcMain.on('set-current-file', (event, filePath) => {
+  currentFile = filePath;
+});
+
 ipcMain.on('export-spreadsheet', (event, { content, format }) => {
   const outputFile = dialog.showSaveDialogSync(mainWindow, {
     defaultPath: currentFile.replace(/\.[^/.]+$/, `.${format}`),
@@ -452,7 +470,20 @@ function extractTablesFromMarkdown(markdown) {
   return tables;
 }
 
-app.whenReady().then(createWindow);
+app.whenReady().then(() => {
+  createWindow();
+  
+  // Handle file association on app startup
+  // Process all command line arguments except the first two (node and script path)
+  const fileArgs = process.argv.slice(2);
+  for (const arg of fileArgs) {
+    if ((arg.endsWith('.md') || arg.endsWith('.markdown')) && fs.existsSync(arg)) {
+      // Store the file to open after window is ready
+      app.pendingFile = arg;
+      break;
+    }
+  }
+});
 
 app.on('window-all-closed', () => {
   if (process.platform !== 'darwin') {
@@ -464,4 +495,26 @@ app.on('activate', () => {
   if (BrowserWindow.getAllWindows().length === 0) {
     createWindow();
   }
-});
+});
+
+// Handle file opening on macOS
+app.on('open-file', (event, filePath) => {
+  event.preventDefault();
+  if (mainWindow) {
+    openFileFromPath(filePath);
+  } else {
+    // Store the file path to open after window is created
+    app.pendingFile = filePath;
+  }
+});
+
+// Handle file opening from command line or file association
+function openFileFromPath(filePath) {
+  if (fs.existsSync(filePath)) {
+    currentFile = filePath;
+    const content = fs.readFileSync(filePath, 'utf-8');
+    if (mainWindow && mainWindow.webContents) {
+      mainWindow.webContents.send('file-opened', { path: filePath, content });
+    }
+  }
+}

src/styles.css

@@ -16,6 +16,93 @@ body {
     height: 100vh;
 }
 
+/* Tab Bar */
+.tab-bar {
+    display: flex;
+    align-items: center;
+    background: #f0f0f0;
+    border-bottom: 1px solid #ddd;
+    padding: 0 8px;
+    min-height: 36px;
+}
+
+.tab {
+    display: flex;
+    align-items: center;
+    padding: 6px 12px;
+    background: #e8e8e8;
+    border: 1px solid #ccc;
+    border-bottom: none;
+    border-radius: 6px 6px 0 0;
+    margin-right: 2px;
+    cursor: pointer;
+    user-select: none;
+    max-width: 200px;
+    min-width: 120px;
+}
+
+.tab.active {
+    background: #fff;
+    border-color: #999;
+    z-index: 1;
+}
+
+.tab-title {
+    flex: 1;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+    font-size: 13px;
+}
+
+.tab-close {
+    background: none;
+    border: none;
+    font-size: 16px;
+    font-weight: bold;
+    cursor: pointer;
+    padding: 0;
+    margin-left: 8px;
+    width: 16px;
+    height: 16px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    border-radius: 3px;
+    color: #666;
+}
+
+.tab-close:hover {
+    background: #ddd;
+    color: #000;
+}
+
+.new-tab-button {
+    background: none;
+    border: 1px solid #ccc;
+    border-radius: 4px;
+    padding: 4px 8px;
+    cursor: pointer;
+    font-size: 14px;
+    margin-left: 8px;
+    color: #666;
+}
+
+.new-tab-button:hover {
+    background: #e8e8e8;
+}
+
+/* Tab Content */
+.tab-content {
+    display: flex;
+    flex: 1;
+    overflow: hidden;
+}
+
+.tab-content:not(.active) {
+    display: none;
+}
+
 /* Toolbar */
 .toolbar {
     display: flex;
@@ -65,8 +152,40 @@ body {
 .pane {
     flex: 1;
     overflow: auto;
+    min-width: 0;
 }
 
+.pane:first-child {
+    border-right: 1px solid #ddd;
+}
+
+.editor-textarea {
+    width: 100%;
+    height: 100%;
+    padding: 20px;
+    font-family: 'SF Mono', Monaco, 'Courier New', monospace;
+    font-size: 15px;
+    line-height: 1.6;
+    border: none;
+    outline: none;
+    resize: none;
+}
+
+.pane:last-child {
+    padding: 0;
+    background: #fff;
+}
+
+.preview-content {
+    max-width: none;
+    margin: 0;
+    padding: 20px 24px 24px 24px;
+    line-height: 1.6;
+    font-size: 15px;
+    font-size: 14px;
+}
+
+/* Legacy support for old selectors */
 #editor-pane {
     border-right: 1px solid #ddd;
 }
@@ -76,7 +195,7 @@ body {
     height: 100%;
     padding: 20px;
     font-family: 'SF Mono', Monaco, 'Courier New', monospace;
-    font-size: 14px;
+    font-size: 15px;
     line-height: 1.6;
     border: none;
     outline: none;
@@ -91,6 +210,7 @@ body {
 #preview {
     max-width: 800px;
     margin: 0 auto;
+    font-size: 15px;
 }
 
 /* Status Bar */
@@ -105,31 +225,33 @@ body {
 }
 
 /* Preview Styles */
-#preview h1, #preview h2, #preview h3, #preview h4, #preview h5, #preview h6 {
+#preview h1, #preview h2, #preview h3, #preview h4, #preview h5, #preview h6,
+.preview-content h1, .preview-content h2, .preview-content h3, .preview-content h4, .preview-content h5, .preview-content h6 {
     margin-top: 24px;
     margin-bottom: 16px;
     font-weight: 600;
     line-height: 1.25;
 }
 
-#preview h1 {
+#preview h1, .preview-content h1 {
     font-size: 2em;
     border-bottom: 1px solid #eaecef;
     padding-bottom: 0.3em;
+    margin-top: 0;
 }
 
-#preview h2 {
+#preview h2, .preview-content h2 {
     font-size: 1.5em;
     border-bottom: 1px solid #eaecef;
     padding-bottom: 0.3em;
 }
 
-#preview p {
+#preview p, .preview-content p {
     margin-bottom: 16px;
     line-height: 1.6;
 }
 
-#preview code {
+#preview code, .preview-content code {
     padding: 0.2em 0.4em;
     margin: 0;
     font-size: 85%;
@@ -138,7 +260,7 @@ body {
     font-family: 'SF Mono', Monaco, 'Courier New', monospace;
 }
 
-#preview pre {
+#preview pre, .preview-content pre {
     padding: 16px;
     overflow: auto;
     font-size: 85%;
@@ -148,7 +270,7 @@ body {
     margin-bottom: 16px;
 }
 
-#preview pre code {
+#preview pre code, .preview-content pre code {
     display: inline;
     max-width: auto;
     padding: 0;
@@ -160,54 +282,54 @@ body {
     border: 0;
 }
 
-#preview blockquote {
+#preview blockquote, .preview-content blockquote {
     padding: 0 1em;
     color: #6a737d;
     border-left: 0.25em solid #dfe2e5;
     margin-bottom: 16px;
 }
 
-#preview ul, #preview ol {
+#preview ul, #preview ol, .preview-content ul, .preview-content ol {
     padding-left: 2em;
     margin-bottom: 16px;
 }
 
-#preview li {
+#preview li, .preview-content li {
     margin-bottom: 4px;
 }
 
-#preview a {
+#preview a, .preview-content a {
     color: #0366d6;
     text-decoration: none;
 }
 
-#preview a:hover {
+#preview a:hover, .preview-content a:hover {
     text-decoration: underline;
 }
 
-#preview img {
+#preview img, .preview-content img {
     max-width: 100%;
     height: auto;
 }
 
-#preview table {
+#preview table, .preview-content table {
     border-collapse: collapse;
     margin-bottom: 16px;
     width: 100%;
 }
 
-#preview table th,
-#preview table td {
+#preview table th, #preview table td,
+.preview-content table th, .preview-content table td {
     padding: 6px 13px;
     border: 1px solid #dfe2e5;
 }
 
-#preview table th {
+#preview table th, .preview-content table th {
     font-weight: 600;
     background-color: #f6f8fa;
 }
 
-#preview table tr:nth-child(2n) {
+#preview table tr:nth-child(2n), .preview-content table tr:nth-child(2n) {
     background-color: #f6f8fa;
 }
 
@@ -217,6 +339,40 @@ body.theme-dark {
     color: #d4d4d4;
 }
 
+body.theme-dark .tab-bar {
+    background: #2d2d30;
+    border-bottom-color: #3e3e42;
+}
+
+body.theme-dark .tab {
+    background: #3c3c3c;
+    border-color: #555;
+    color: #d4d4d4;
+}
+
+body.theme-dark .tab.active {
+    background: #1e1e1e;
+    border-color: #666;
+}
+
+body.theme-dark .tab-close {
+    color: #ccc;
+}
+
+body.theme-dark .tab-close:hover {
+    background: #555;
+    color: #fff;
+}
+
+body.theme-dark .new-tab-button {
+    border-color: #555;
+    color: #ccc;
+}
+
+body.theme-dark .new-tab-button:hover {
+    background: #3c3c3c;
+}
+
 body.theme-dark .toolbar {
     background: #2d2d30;
     border-bottom-color: #3e3e42;
@@ -235,6 +391,20 @@ body.theme-dark .toolbar-separator {
     background: #3e3e42;
 }
 
+body.theme-dark .pane:first-child {
+    border-right-color: #3e3e42;
+}
+
+body.theme-dark .editor-textarea {
+    background: #1e1e1e;
+    color: #d4d4d4;
+}
+
+body.theme-dark .pane:last-child {
+    background: #1e1e1e;
+}
+
+/* Legacy support */
 body.theme-dark #editor-pane {
     border-right-color: #3e3e42;
 }
@@ -248,42 +418,42 @@ body.theme-dark #preview-pane {
     background: #252526;
 }
 
-body.theme-dark #preview {
+body.theme-dark #preview, body.theme-dark .preview-content {
     color: #d4d4d4;
 }
 
-body.theme-dark #preview h1,
-body.theme-dark #preview h2 {
+body.theme-dark #preview h1, body.theme-dark #preview h2,
+body.theme-dark .preview-content h1, body.theme-dark .preview-content h2 {
     border-bottom-color: #3e3e42;
 }
 
-body.theme-dark #preview code {
+body.theme-dark #preview code, body.theme-dark .preview-content code {
     background-color: rgba(255,255,255,0.1);
 }
 
-body.theme-dark #preview pre {
+body.theme-dark #preview pre, body.theme-dark .preview-content pre {
     background-color: #2d2d30;
 }
 
-body.theme-dark #preview blockquote {
+body.theme-dark #preview blockquote, body.theme-dark .preview-content blockquote {
     color: #808080;
     border-left-color: #3e3e42;
 }
 
-body.theme-dark #preview a {
+body.theme-dark #preview a, body.theme-dark .preview-content a {
     color: #569cd6;
 }
 
-body.theme-dark #preview table th,
-body.theme-dark #preview table td {
+body.theme-dark #preview table th, body.theme-dark #preview table td,
+body.theme-dark .preview-content table th, body.theme-dark .preview-content table td {
     border-color: #3e3e42;
 }
 
-body.theme-dark #preview table th {
+body.theme-dark #preview table th, body.theme-dark .preview-content table th {
     background-color: #2d2d30;
 }
 
-body.theme-dark #preview table tr:nth-child(2n) {
+body.theme-dark #preview table tr:nth-child(2n), body.theme-dark .preview-content table tr:nth-child(2n) {
     background-color: #2d2d30;
 }
 
@@ -299,6 +469,40 @@ body.theme-solarized {
     color: #657b83;
 }
 
+body.theme-solarized .tab-bar {
+    background: #eee8d5;
+    border-bottom-color: #93a1a1;
+}
+
+body.theme-solarized .tab {
+    background: #fdf6e3;
+    border-color: #93a1a1;
+    color: #657b83;
+}
+
+body.theme-solarized .tab.active {
+    background: #fdf6e3;
+    border-color: #859900;
+}
+
+body.theme-solarized .tab-close {
+    color: #657b83;
+}
+
+body.theme-solarized .tab-close:hover {
+    background: #93a1a1;
+    color: #dc322f;
+}
+
+body.theme-solarized .new-tab-button {
+    border-color: #93a1a1;
+    color: #657b83;
+}
+
+body.theme-solarized .new-tab-button:hover {
+    background: #eee8d5;
+}
+
 body.theme-solarized .toolbar {
     background: #eee8d5;
     border-bottom-color: #93a1a1;
@@ -318,19 +522,19 @@ body.theme-solarized #editor {
     color: #657b83;
 }
 
-body.theme-solarized #preview {
+body.theme-solarized #preview, body.theme-solarized .preview-content {
     color: #586e75;
 }
 
-body.theme-solarized #preview code {
+body.theme-solarized #preview code, body.theme-solarized .preview-content code {
     background-color: #eee8d5;
 }
 
-body.theme-solarized #preview pre {
+body.theme-solarized #preview pre, body.theme-solarized .preview-content pre {
     background-color: #eee8d5;
 }
 
-body.theme-solarized #preview a {
+body.theme-solarized #preview a, body.theme-solarized .preview-content a {
     color: #268bd2;
 }
 
@@ -340,6 +544,40 @@ body.theme-monokai {
     color: #f8f8f2;
 }
 
+body.theme-monokai .tab-bar {
+    background: #3e3d32;
+    border-bottom-color: #75715e;
+}
+
+body.theme-monokai .tab {
+    background: #49483e;
+    border-color: #75715e;
+    color: #f8f8f2;
+}
+
+body.theme-monokai .tab.active {
+    background: #272822;
+    border-color: #a6e22e;
+}
+
+body.theme-monokai .tab-close {
+    color: #f8f8f2;
+}
+
+body.theme-monokai .tab-close:hover {
+    background: #75715e;
+    color: #f92672;
+}
+
+body.theme-monokai .new-tab-button {
+    border-color: #75715e;
+    color: #f8f8f2;
+}
+
+body.theme-monokai .new-tab-button:hover {
+    background: #49483e;
+}
+
 body.theme-monokai .toolbar {
     background: #3e3d32;
     border-bottom-color: #75715e;
@@ -359,33 +597,38 @@ body.theme-monokai #editor {
     color: #f8f8f2;
 }
 
+body.theme-monokai .editor-textarea {
+    background: #272822;
+    color: #f8f8f2;
+}
+
 body.theme-monokai #preview-pane {
     background: #272822;
 }
 
-body.theme-monokai #preview {
+body.theme-monokai #preview, body.theme-monokai .preview-content {
     color: #f8f8f2;
 }
 
-body.theme-monokai #preview h1,
-body.theme-monokai #preview h2 {
+body.theme-monokai #preview h1, body.theme-monokai #preview h2,
+body.theme-monokai .preview-content h1, body.theme-monokai .preview-content h2 {
     border-bottom-color: #75715e;
 }
 
-body.theme-monokai #preview code {
+body.theme-monokai #preview code, body.theme-monokai .preview-content code {
     background-color: #3e3d32;
 }
 
-body.theme-monokai #preview pre {
+body.theme-monokai #preview pre, body.theme-monokai .preview-content pre {
     background-color: #3e3d32;
 }
 
-body.theme-monokai #preview blockquote {
+body.theme-monokai #preview blockquote, body.theme-monokai .preview-content blockquote {
     color: #75715e;
     border-left-color: #75715e;
 }
 
-body.theme-monokai #preview a {
+body.theme-monokai #preview a, body.theme-monokai .preview-content a {
     color: #66d9ef;
 }
 
@@ -401,6 +644,40 @@ body.theme-github {
     color: #24292e;
 }
 
+body.theme-github .tab-bar {
+    background: #fafbfc;
+    border-bottom-color: #e1e4e8;
+}
+
+body.theme-github .tab {
+    background: #f6f8fa;
+    border-color: #e1e4e8;
+    color: #24292e;
+}
+
+body.theme-github .tab.active {
+    background: #fff;
+    border-color: #0366d6;
+}
+
+body.theme-github .tab-close {
+    color: #586069;
+}
+
+body.theme-github .tab-close:hover {
+    background: #e1e4e8;
+    color: #cb2431;
+}
+
+body.theme-github .new-tab-button {
+    border-color: #e1e4e8;
+    color: #586069;
+}
+
+body.theme-github .new-tab-button:hover {
+    background: #f6f8fa;
+}
+
 body.theme-github .toolbar {
     background: #fafbfc;
     border-bottom-color: #e1e4e8;
@@ -420,29 +697,29 @@ body.theme-github #editor {
     color: #24292e;
 }
 
-body.theme-github #preview {
+body.theme-github #preview, body.theme-github .preview-content {
     color: #24292e;
 }
 
-body.theme-github #preview h1,
-body.theme-github #preview h2 {
+body.theme-github #preview h1, body.theme-github #preview h2,
+body.theme-github .preview-content h1, body.theme-github .preview-content h2 {
     border-bottom-color: #eaecef;
 }
 
-body.theme-github #preview code {
+body.theme-github #preview code, body.theme-github .preview-content code {
     background-color: rgba(27,31,35,0.05);
 }
 
-body.theme-github #preview pre {
+body.theme-github #preview pre, body.theme-github .preview-content pre {
     background-color: #f6f8fa;
 }
 
-body.theme-github #preview blockquote {
+body.theme-github #preview blockquote, body.theme-github .preview-content blockquote {
     color: #6a737d;
     border-left-color: #dfe2e5;
 }
 
-body.theme-github #preview a {
+body.theme-github #preview a, body.theme-github .preview-content a {
     color: #0366d6;
 }
 
@@ -453,6 +730,15 @@ body.theme-github .status-bar {
 }
 
 /* Hide preview pane by default */
+.pane.hidden {
+    display: none;
+}
+
+.pane.full-width {
+    border-right: none;
+}
+
+/* Legacy support */
 #preview-pane.hidden {
     display: none;
 }