Currently GravityView and it's extensions have a set of styles to work properly with a few of themes in mind so that our users and our team can have a base for comparison on what is the expected behavior from a plugin.
The statement above doesn't mean that GravityView will not work with other themes, it's only to set the expectations right if you are not using one of the themes listed below you might have to change and insert a few CSS rules so that you have a good looking View.
Themes Currently used as a base:
Testing for Conflicts
Sometimes in support one of our team members might ask you to test for conflicts on your themes, with that we want to make sure that you switched back to one of the base themes that our team tests and supports so that it is easier to pinpoint what is the source of the problem.