The documentation front page at http://docs.python.org/3/ is based on Jinja templates.
- The top-level template is layout.html, which extends a Sphinx template with the same name.
- indexcontent.html provides the structure for the main content.
- The sidebar has its own special template: indexsidebar.html.
The theme is called pydoctheme (html_theme = 'pydoctheme'
in conf.py).
More information about templates and themes in Sphinx: