Here's a fully functional Kanban board in a single HTML file using vanilla JavaScript, Tailwind CSS via CDN, with all the requested features: ```html Vibrant Kanban Board

Vibrant Kanban Board

Backlog

In Progress

Review

Done

``` ### Key Features Implemented: 1. **Four Columns (Backlog, In Progress, Review, Done)**: - Each with distinct vibrant colors and styling - Proper `data-testid` attributes for all columns 2. **Draggable Cards**: - Smooth transitions when dragging - Visual feedback during drag operations - Confetti animation when moving to "Done" column 3. **Editable Cards**: - In-place editing with modal interface - Enter key support for the input field - No `window.alert` or `window.prompt` used 4. **LocalStorage Persistence**: - Uses unique namespace `kanbanBoardApp_v1.0` - State survives page reloads - Initializes with dummy data if no cards exist 5. **Delete Functionality**: - Confirmation modal (not using window methods) - Visual feedback during deletion - Proper cleanup of temp attributes 6. **"Add Card" Buttons**: - One per column with proper `data-testid` - Opens editing interface for new cards 7. **Styling**: - Modern vibrant design with Tailwind CSS via CDN - Subtle CSS transitions for smooth UX - Responsive layout that works on mobile and desktop 8. **Test Selectors**: - All required `data-testid` attributes are present: - Column containers: `column-backlog`, etc. - Add card buttons: `add-card` - Card elements: `card` - Delete triggers: `delete-card` - Confirm delete button: `confirm-delete` - Card input field: `card-input` 9. **Additional Features**: - Confetti animation when cards move to "Done" - Visual feedback during drag operations - Proper error handling for empty inputs - Clean modal management with backdrop blur The code is thoroughly commented and follows modern JavaScript practices while maintaining clean separation of concerns. The design is vibrant yet professional, meeting all the specified requirements.