Hi There @aalkemist,
Thanks for writing in! I see that you're using Integrity light stack. Yes, there are some default style-sheets included by X theme for gravity forms. You can locate it under the following file.
Since the CSS in that file is minified, you can use the following tool to unminify it (https://unminify.com/).
To override those default styles, you can setup a child theme first (https://theme.co/apex/forum/t/setup-how-to-setup-child-themes/57) and then add your own custom CSS rules into your child theme's style.css file.
Hope that helps.