CSS Ready Classes are only supported in PDFs when Gravity Forms Legacy mode is enabled via
Form Settings -> Enable legacy markup.
Gravity PDF supports the following official CSS Ready Classes:
When not already in a column the following List classes are also supported:
Four Column Classes
This four-column CSS code has become increasingly popular for Gravity Forms users and so we have added full support for these classes in Gravity PDF (make sure to include the custom CSS with your theme to get the same effect on the front end).
To start using in your PDF, add the classes
gf_fourth_quarter to your Gravity Forms fields and supported PDF templates will automatically create a four column layout to match.
Adding to Form
Add the appropriate CSS Ready Class to your field's Custom CSS Class setting in the Form Editor, which is located under the Appearance setting.