HTML as originally proposed had a lot of features that allowed page designers to specify the appearance of the page in detail. However, XHTML tries to separate presentation—the fine details such as fonts, colors, and spacing—from structure and content.
The preferred way to specify presentation is to use CSS (Cascading Stylesheet Language) to write a stylesheet that describes presentation details, and place it in a separate file from the XHTML.
CSS is described in a separate publication, Styling Web pages with CSS-2.
When you write your XHTML page, use a
link element to connect that page with its stylesheet.
See Section 8.4, “The
link element: Related documents”.
The good news is that you don't have to use CSS. If browsers render your page in a reasonable way, there's no reason to use CSS.