[Andreas]

There are 4 types:

• template
  These are normal templates (like header, footer, navbar, etc.)
• css
  These are CSS definitions
• stylevar
  These are style variables (like image paths, widths, etc.)
• replacement
  These are replacement variables

You can't create CSS definitions via AdminCP, you must add them directly in the DB.
You will also need at least 2 Plugins inf you want to create your own CSS definitions (that's what CSS "templates" are).