Read: Every Layout by Heydon Pickering & Andy Bell

Read a very nice book about foundations of CSS lay outing (think box model and centering, not styling) Relearn CSS layout: Every Layout. Also the accompanying website is well worth the prize (both included in the bundle price). Helps one grasp on how to think about building a web site from principals and basic building blocks. Recommend it strongly to anyone who struggles to understand CSS like me