There is no way to add separation lines at the moment. Have you considered creating different tabs, accordions or stacks for organizing your parameters?
What do you already do? And what do you mean by “the single line was our goal”?
If you use the “Getting started” theme, you will notice that all contour lines are removed from the UI, because the property is applied on the “Paper” element (which is used by all widgets).
If you only want to remove the contour lines from the parameters, you can do this:
Thanks alot for the help. Also, thanks for appbuilder. I’m not fluent in web development at all and it’s awesome to create these interfaces within grasshopper (that I am fluent).
Keep up with the good work.
ps: would be awesome in the future to have a theme customizer in a web page or a gh definition