Styling XML Documents with CSS: Enhancing XML Presentation (with Considerations)

Explore using CSS to style XML documents, understanding its limitations and the recommended approach (XSLT). This tutorial demonstrates applying CSS styles to XML, explaining the necessary steps (using processing instructions), and emphasizing the best practice of using XSLT for XML styling.

Styling XML Documents with CSS

While CSS (Cascading Style Sheets) is primarily used for styling HTML documents, it can also be applied to XML documents to control their visual presentation. However, it's important to note that CSS is not the standard or recommended way to style XML. The World Wide Web Consortium (W3C) recommends using XSLT (Extensible Stylesheet Language Transformations) for styling XML.

Linking XML and CSS

To apply CSS styles to an XML document, you need to link the CSS stylesheet to the XML document using the `type` attribute in the `` processing instruction within the XML document's prolog:

<?xml-stylesheet type="text/css" href="mystyles.css"?>

Example: Styling an XML Document with CSS

This example demonstrates styling an XML file (`employee.xml`) using a CSS stylesheet (`cssemployee.css`) and a Document Type Definition (DTD) file (`employee.dtd`).

`cssemployee.css` (CSS Stylesheet)

employee {
  background-color: pink;
}
firstname, lastname, email {
  font-size: 25px;
  display: block;
  color: blue;
  margin-left: 50px;
}

`employee.dtd` (DTD File)

employee.dtd

<!ELEMENT employee (firstname, lastname, email)>
<!ELEMENT firstname (#PCDATA)>
<!ELEMENT lastname (#PCDATA)>
<!ELEMENT email (#PCDATA)>
        

Explanation

• <!ELEMENT employee (firstname, lastname, email)>: Defines the `employee` element that must contain the `firstname`, `lastname`, and `email` elements, in that order.
• <!ELEMENT firstname (#PCDATA)>: Defines the `firstname` element as containing parsed character data (text).
• <!ELEMENT lastname (#PCDATA)>: Defines the `lastname` element as containing parsed character data (text).
• <!ELEMENT email (#PCDATA)>: Defines the `email` element as containing parsed character data (text).

Example XML Document Based on the DTD

The following is an example of how the XML document would look that conforms to the above DTD:

<employee>
  <firstname>John</firstname>
  <lastname>Doe</lastname>
  <email>john.doe@example.com</email>
</employee>
        

`employee.xml` (XML File)

<?xml-stylesheet type="text/css" href="cssemployee.css"?>
<!DOCTYPE employee SYSTEM "employee.dtd">
<employee>
  <firstName>Vimal</firstName>
  <lastName>Jaiswal</lastName>
  <email>vimal@tutorialsarena.com</email>
</employee>

Using XSLT (Recommended)

In this example, we use CSS to apply styles directly to an XML document. However, note that CSS can only be used for simple styling of XML documents.

<?xml version="1.0" encoding="UTF-8"?>
<library>
  <book>
    <title>XML for Beginners</title>
    <author>Sam Brown</author>
  </book>
  <book>
    <title>Advanced XML</title>
    <author>Sarah Lee</author>
  </book>
</library>
        

Example: Styling XML with CSS

CSS can be used with XML to apply basic styles to the XML tags, but it lacks the ability to manipulate the structure of the document:

library {
  font-family: Arial, sans-serif;
  color: darkblue;
}

book {
  margin: 10px 0;
}

title {
  font-weight: bold;
  font-size: 1.2em;
}

author {
  color: gray;
}
        

Limitations of Using CSS with XML

• CSS cannot modify the structure of the XML document.
• It is more suitable for simple visual formatting, such as changing font sizes or colors.
• For more complex transformations, like sorting data or adding conditional logic, XSLT is recommended.

Recommended Approach: Using XSLT for XML Transformation

XSLT provides a more robust and powerful method for transforming XML documents, including the ability to:

• Apply complex logic to transform the XML into other formats (e.g., HTML, plain text).
• Sort, filter, or conditionally modify XML elements.
• Produce dynamic content based on XML data.

Example: Basic XSLT Transformation

Here’s an example of how XSLT can be used to transform XML data into an HTML format:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:template match="/library">
    <html>
      <body>
        <h1>Book List</h1>
        <ul>
          <xsl:for-each select="book">
            <li>
              <b><xsl:value-of select="title"/></b>
              by <xsl:value-of select="author"/>
            </li>
          </xsl:for-each>
        </ul>
      </body>
    </html>
  </xsl:template>

</xsl:stylesheet>
        

Explanation of XSLT Example

In this XSLT example, the `` directive iterates over each `` element in the XML document, transforming it into an HTML list item (`