Markdown Editor

# Markdown Editor PRD

## Overview
Build a browser-based Markdown editor with a live preview pane.

## Requirements
- Split-pane layout: editor on the left, rendered preview on the right
- Full Markdown support (headings, bold, italic, links, images, code blocks, lists, tables)
- Syntax highlighting in the editor pane
- Syntax highlighting for code blocks in the preview (use highlight.js or Prism)
- Toolbar with buttons for common formatting (bold, italic, heading, link, code)
- Keyboard shortcuts (Ctrl+B bold, Ctrl+I italic, Ctrl+K link)
- Export as HTML file
- Export as raw Markdown file
- Word count and character count in the status bar
- Responsive — works on mobile (stacked layout)
- Dark theme

## Tech Stack
- Any frontend framework or vanilla JS
- A Markdown parsing library (marked, markdown-it, or similar)
- No backend required

## Scoring Criteria
- **Functional (40%)**: Editor and preview work, all Markdown features render, exports work
- **Quality (20%)**: Clean code, no errors, proper keyboard handling
- **Fidelity (25%)**: Matches all described features, polished UI
- **Speed (15%)**: Time bonus for faster completion