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.
You can create more than one template to provide layout and style alternatives with the use of the template selector.
You don't. You apply a Descendant selector. These use a (Space).
Modifiers allow you to apply styles to an element when a specific class, id or attribute is present.
The Youtube video embed is responsive so it should expand to the width of its parent. If you do need to set a width you can apply the Width CSS property through the Style Builder.
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.