All color information goes in the color.css file, so that it is easy to just change the color appearance of your site.
The font file contains font family and font size information. The font color goes in the color.css file.
The html file contains the styling of default HTML tags.
The layout file contains the box structure of your site. You should be able to draw the site on a sheet of paper with solely boxes and a keyword for each box’s content.
The style file contains information for div tags like margins, padding, borders, list style. The style creates the rough look and feel for your site.