fixed, unified many parts of content retrieval from markdown

- Deprecated most of our spreadsheet data as it is no longer necessary, and moved what is necessary to  a few sheets instead of one per stage [Note: these changes aren't reflected in the code]

- Lots of small changes made to synchronize the spreadsheet and the few places where templates still access it

- Fixed the page design as reflected in the markdown content (mostly moved around design elements to be where we had originally intended them)

- Also changed styling of markdown content to use CSS classes (easier to manage)