Nextstrain Sphinx Theme

A Sphinx theme for Nextstrain’s documentation, based on Read The Docs’ default theme (sphinx_rtd_theme).


This theme is distributed on PyPI as nextstrain-sphinx-theme and can be installed with pip:

$ python3 -m pip install nextstrain-sphinx-theme

To use the theme in your Sphinx project, you will need to add the following to your file:

html_theme = "nextstrain-sphinx-theme"

This theme is based on sphinx_rtd_theme and accepts most of the same configuration options settable via html_theme_option and a few additional options as well:


Boolean determining if the Nextstrain logo should be displayed. Defaults to true.


URL to use for the logo’s link. Defaults to <>.


Ignored. Inherited from sphinx_rtd_theme. Instead, the project name and version info will not be displayed (thus showing only the logo) when subproject is true.


Boolean determining if this is a subproject of the main Nextstrain documentation project on <>. Defaults to true.

If your project wants to display its own logo, just set Sphinx’s html_logo to point to the image file in your Sphinx project.

html_logo = "_static/your-logo.png"

This will automatically take precedence over the default Nextstrain logo provided by the theme.


python3 -m pip install -e .
make clean # not always needed, but better to be cautious
make html
open build/html/index.html


  1. Make sure all your changes have been commited to the main branch.

  2. Add a commit which describes the changes from the previous version to CHANGES.rst and updates the version number in lib/nextstrain/sphinx/theme/VERSION.

  3. Tag this commit with the version number, e.g. git tag -a 2020.4 -m "version 2020.4".

  4. Push the commit and tag to GitHub, e.g. git push origin main 2020.4.

  5. Publish to PyPI by invoking a GitHub Actions workflow:

    1. Go to the workflow: publish.yml.

    2. Select Run workflow. In the new menu:

      1. Select Use workflow from > Tags > new version number (e.g. 2020.4).

      2. Set PyPI instance for publishing as PyPI (default) or TestPyPI. More info

      3. Select Run workflow.


PR test builds are available here: and usually follow the following URL path convention: https://nextstrain– where 17 is the PR number