Quarto 1.3 includes the following new features:

Confluence Publishing—Publish quarto documents and projects to Confluence spaces.
Multi-Format Publishing—Simple discovery of other formats for HTML documents.
Jupyter Cell Embedding—Embed code and outputs from Jupyter Notebooks in Quarto documents.
Article Grid Customization—Customize the widths within the article grid in HTML documents.
Code Block Annotation—Use annotation to provide contextual comments to help readers understand code.
Quarto Book AsciiDoc Support—Output Quarto books to AsciiDoc files
Website Navigation Improvements—Improved navigation for Quarto websites.
Mermaid Diagram Theming—Mermaid diagram’s appearance automatically matches your document’s theme (or customize it)
PDF: SVG and Remote Images—Improved handling for SVG images and remote images in PDF documents.
kbd Shortcode—Show well formatted keyboard shortcuts in Quarto documents.
Extensions: Quarto AST—Use custom AST nodes for Quarto types like Callout when writing extensions.
Extensions: HTML Tables—HTML tables are now processed and accessible to Lua filters in all formats (not just HTML).

See the Pre-Release Download Page for a complete list of all the changes and bug fixes.