Broke my articles’ design

I would like to use that plugin, it has really good options for customizing design.

However, when I installed it and set up for my blog (Twenty-Nineteen theme), it broke some elements of in-article design. The areas where I switched a background color to green with default Gutenberg block editor, became blue (seems like it’s the default theme color). Not sure what was that but I don’t want to experiment with the non-stable plugin since I just launched an ad campaign for my new article.