I would never go the
plain text route unless the source styling has been destroyed by discarding or substituting (the wrong) CSS.
Reverse engineer what you have. The Code inspector in Book View will help decode the style Cascades you need to look at.
I use 'free CSS Toolbox' (the installer loads a lot of buy these favorites
, which is why I don't make this a link) to sort my stylesheet to make finding a selector easier.
Learn basic CSS.. Think
Contained boxes (Each outer box can affect an inner box, so start there)