This may happen if the Style Sheet was using Media Queries or Print Styles.
In BBPS 2.0, we added the ability to apply any media targeting applied to the style sheet.
Print Styles are still not available to be added. We are currently evaluating this issue and will update this article when we have more information.
1. Use an "Event Registration Form (Classic)" part type instead of the "Event Registration Form" part type. (The "Classic" version of the part type does not connect to the Blackbaud Secure Payments page.)
Alternate solution: Remove the print styles from the style sheets and then manually update the secure payment templates.