docbook.css.source string
docbook.css.source Name of the default CSS input file
docbook.css.xml

## Description

The docbook.css.source parameter specifies the name of the file containing the default DocBook CSS styles. Those styles are necessary when the make.clean.html parameter is nonzero.

The file is a well-formed XML file that must consist of a single style root element that contains CSS styles as its text content. The default value of the parameter (and filename) is `docbook.css.xml`. The stylesheets ship with the default file. You can substitute your own and specify its path in this parameter.

If docbook.css.source is not blank, and make.clean.html is nonzero, then the stylesheet takes the following actions:

1. The stylesheet uses the XSLT `document()` function to open the file specified by the parameter and load it into a variable.

2. The stylesheet forms an output pathname consisting of the value of the base.dir parameter (if it is set) and the value of docbook.css.source, with the `.xml` suffix stripped off.

3. The stylesheet removes the style wrapper element and writes just the CSS text content to the output file.

4. The stylesheet adds a link element to the HTML HEAD element to reference the external CSS stylesheet. For example:

       <link rel="stylesheet" href="docbook.css" type="text/css">

   However, if the docbook.css.link parameter is set to zero, then no link is written for the default CSS file. That is useful if a custom CSS file will import the default CSS stylesheet to ensure proper cascading of styles.

If the docbook.css.source parameter is changed from its default `docbook.css.xml` to blank, then no default CSS is generated. Likewise if the make.clean.html parameter is set to zero, then no default CSS is generated. The custom.css.source parameter can be used instead to generate a complete custom CSS file.

You can use the generate.css.header parameter to instead write the CSS to each HTML HEAD element in a style tag instead of an external CSS file.