XML lacks some tags that are often used in HTML. It therefore becomes necessary to use stylesheets along with XML and DTD. The Computer Technology Documentation Project has an XML Example that illustrates an implementation of XML, DTD and CSS. The interaction of these three types of file are sufficiently complicated that a novice like myself could use a stripped-down version of the example. The coding for this version is shown below:
The identifier PARTS1 appears in the file names for the XML and DTD files; in DOCTYPE (two places);and in the body of the XML code. PARTS1 also shows up as an ELEMENT of parts1.dtd and in the first line of easy.css.
When you see the humble browser view of parts1.xml, you realize that XML can be a complicated way of doing something that is easy in HTML. There are also easy-to-code XML pages such as this brief writeup.