Indenting Expanded Posts or Removing Arrows on "Kubrick" Style

I’m trying to edit the style of my sidebar. Ideally, I would like to be able to click on a category and the expanded posts underneath to indent to the right. I do not want to use any symbols/characters to express this. I simply want to be able to differentiate category and post by the indentation (and perhaps by color).

The closest I have gotten to this is by changing the widget settings to a custom expand character (leaving it blank), and using the Kubrick style. This provides me with an indentation of the expanded posts, however, it also applies the double arrow symbol in front of each post.

Does anyone have any tips for removing the symbols while using this style? Or any codes that would enable me to create a custom indentation?

I am not strong with code, so if you could be specific as to what template/file I need to edit, I would very much appreciate it.

You can view my website to better understand:
krystlemerrow.com

https://www.ads-software.com/extend/plugins/collapsing-categories/