CSS

The advantages to using CSS include:

That once set up it saves an enormous amount of time.

It means that, especially on a large site, the template can be designed so that there is no need to redo the styles for every page.

When page styles need to be edited or even just experimented with, various options can be tested very quickly.

With CSS templates site style and layout elements can be altered according to the template's capacity/design. It doesn't change the information content.

By customising the CSS all the design elements and layout of a site can be altered. It doesn't change the information content.

Accessibility is important because it enables people who have disabilities, particularly with sight to modify the information so that they can access it.

I customised the CSS on links within this site.

A good reference for CSS can be found at:

http://www.w3schools.com/css/default.asp