Apply css to all element except one who has specific parent

Question

I want to apply CSS to all pages except sidebars. Let me show you an example

.page #buddypress ul.group li

Answer 1

You can override all css for that element by using its ID (css id overrides css class). A possibility would be:

#id{all:unset}

However, this has limited browser support and your specified element should have an ID.
See also: https://stackoverflow.com/a/36892781/9204431