CSS can be added to your pages at 3 different levels.
It is possible to create CSS styles that only work for the single tag it is defined for.
Single tag CSS is used when the style is used in a single place on the entire site.
Usually a certain style appears more than once on your pages, and thus you should use the second technique: adding styles that are defined once for the entire page.
If, however, that certain style is used on more than a single page, you should use the third - and most powerful - technique described: adding styles that are defined once for the entire site.
The following pages will explain each of these techniques....