Remove inline styles on confirmation message

The all_fields helper uses a table layout with a lot of inline styles, as you have discovered. There is no filter to remove those inline styles. If you'd like complete control over the styling of the confirmation message, you can craft your own HTML and insert the merge tags for each field.

If you need additional assistance with that, please post a link to your form. Thank you.

The {all_fields} helper has hard coded table and inline styles in it. There is no filter to work around that output. If you want more control over the display of the output in your confirmation you will have to use your own HTML and styles. You can use conditional shortcodes to limit the display when their was no data input.

http://www.gravityhelp.com/documentation/page/Shortcodes#Conditional_Shortcode

You could also craft your own confirmation message and include logic in it to output only fields which have data in them. You can use the gform_confirmation filter to craft your own confirmation message based on submitted values http://www.gravityhelp.com/documentation/page/Gform_confirmation

The {all_fields} helper has a specific use and it does not appear that your use is one of them. To have complete control over the look of the confirmation, you will have to create it yourself.

The gform_confirmation filter is documented here, with examples of how to change the confirmation:
http://www.gravityhelp.com/documentation/page/Gform_confirmation (lines 7 and 8 in the second example is where you would place all your conditions.)

I brought your other suggestions to the attention of the developers. Thank you for your comments.