As you can see, every page is set to Generator and I have given it custom colors. This all you need to do if you just want to change the colors. The image below shows the result of JUST changing the custom colors.
Overrides: Identifying the Page Setup Pieces aka Style Variables
If you'll notice, when you go to "Custom Options", the description mentions "style variables" and provides a link to Livejournal where they are explained in more technical terms. This image shows what you are altering when you play with the style variables. They are basically a template for parts of the page. You'll probably also notice that these are often altered in overrides.
Overrides: Identifying the Stylesheet Pieces
Do stylesheets scare you with the code? Do they frustrate you because you can't figure out how to alter a certain piece? Well, here are the pieces. Note: The order in which you list the pieces in your stylesheet DOES affect how they are used. Whatever is at the end of the stylesheet takes precedence over what is at the beginning of the stylesheet. So, you should go from general to specific when listing your style. Also, the ENTIRE PAGE after the body is contained within a div tag that centers everything on the page. I felt like I should point that out.
For more information on CSS and stylesheets, check out the CSS standards at W3 Schools.
Questions/Feedback/Discussion?
Leave a comment to this post. I've meddled a lot with overrides, so if you can't figure something out or want to replicate someone else's overrides, but don't know how, drop a comment to this post or make a post in the community (like several others already have) and someone should be able to help you. No question is stupid. So, ask away. Thanks!