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You can adjust the font in a couple ways. For fields like the heading you can double click on it, and then using the toolbar->font size drop down to select a new size.
For other fields we allow you in include custom CSS. See this document for reference:
1) Click on the Setup & Embed tab
2) Select Preferences
3) Select Form Styles
4) Select Inject Custom CSS field
To stylize the street address, we would inject this CSS code to increase the font size, and change the color.
This produces the following:
Let us know if you need further assistance with adding custom CSS. Thanks!