Using styles, you can customize the look of your exported documents in Ulysses III. To create or edit styles, open “Ulysses > Preferences > Styles”. Ulysses comes with a number of built-in styles which you can use right-away. However, you can also tweak them or insert your own styles.
Generally, we recommend starting with one of the built-in styles: double-click one and select “Duplicate” to create a copy. Double-click the copy again and select “Edit” to view and modify it in your favorite text editor. You can then use the new style in Quick Export or during Export Preview.
You can style HTML and ePub documents just using regular CSS files. To insert add your own CSS files, simply drag them into the style preferences table or use the “Add Styles…” button.
For styling Rich Text Formats like RTF and PDF, you can use a custom CSS-like file format called Ulysses Style Sheets – ULSS. This format can be edited just like CSS with a text editor. We've created some plugins for TextMate 2 and Sublime Text 2 that add syntax highlighting and autocompletion for ULSS. There is also a simple syntax highlighting plugin for BBEdit and TextWrangler.
You can also learn more about ULSS on the following pages: