All of your CSS is controlled under admin > customize > themes, by “CSS for the category” I meant that you can target a specific category because we add CSS classes to the page when relevant.
So in the case of a category named “Other” we add the .category-other class to the page’s body tag, so you can use something like this in your general customizations to target that specific category.
body.category-other {
// your CSS for the category here
}