The AsciiDoc theme attribute is used to select an alternative CSS stylesheet and to optionally include additional JavaScript code.

• Theme files reside in an AsciiDoc configuration directory named themes/<theme>/ (where <theme> is the the theme name set by the theme attribute). asciidoc(1) sets the themedir attribute to the theme directory path name.
• The theme attribute can also be set using the asciidoc(1) --theme option, the --theme option can also be used to manage theme plugins.
• AsciiDoc ships with two themes: flask and volnitsky.
• The <theme>.css file replaces the default asciidoc.css CSS file.
• The <theme>.js file is included in addition to the default asciidoc.js JavaScript file.
• If the data-uri attribute is defined then icons are loaded from the theme icons sub-directory if it exists (i.e. the iconsdir attribute is set to theme icons sub-directory path).
• Embedded theme files are automatically inserted in the output files but you need to manually copy linked CSS and Javascript files to the location of the output documents.
• Linked CSS and JavaScript theme files are linked to the same linked locations as other CSS and JavaScript files.

For example, the command-line option --theme foo (or --attribute theme=foo) will cause asciidoc(1) to search configuration file locations 1 for a sub-directory called themes/foo containing the stylesheet foo.css and optionally a JavaScript file name foo.js.