How do I add a combinator to my style?
You can only add combinators to child selectors. Add a child selector and combinator will appear in the Style tree.
Acquia Cohesion renames to Site Studio from version 6.2. Tell me more.
Custom styles are CSS styles for classes.
You don't. You apply a Descendant selector. These use a (Space).
The WYSIWYG (ckeditor) adds a paragraph tag around the text within the block quote. This causes it to inherit the text size of your paragraph base style.