You can change the appearance of the headings displayed in the Document Map pane, as well as the highlight color of the active heading in the pane. The changes you make to the text in the Document Map will not affect the text in the document.
To set the font and font size, click Font, and then make your changes in the font and size boxes.
To set the highlight color, click Border, click the Shading tab, and then select the Fill color you want.