This issue is a continuation of #26809 and aims to migrate the scikit-learn website towards pydata-sphinx-theme. As this is an ambitious goal, this issue is to track the steps of the migration. cc @lucyleeow who guided me to open this issue.

Quick links

• The new_web_theme branch
• Tracker for upstream issues
• Live preview: https://scikit-learn.org/_pst_preview

TODO before merging into main

• doc-min-dependencies is bypassed in CI for now and we need to reactivate it before merging into main. Also, we need to make sure all dependencies are documented, in particular sphinx-design which was not added in the very first setup PR. See also #28379.
• Remove the new_web_theme part in .circleci/config.yml.
• In conf.py, change the version switcher link to https://scikit-learn.org/dev/_static/versions.json.
• Remove themes/ and update exclude_patterns in conf.py: these are only useful for the old theme.
• Pin higher versions of sphinx, pydata-sphinx-theme, and sphinx-gallery. See also tracker for upstream issues.

Tracking work towards the new_web_theme branch

• DOC [PST] conf, setup, general styling #28132
• DOC [PST] landing page #28331
• DOC [PST] install page #28336
• DOC [PST] version switcher and warning banner #28347
• MAINT [PST] set up live preview #28353
• DOC [PST] fix lock files and add sphinx-design #28379
• DOC [PST] fix dropdowns #28401
• DOC [PST] fix changelog badges #28409
• DOC [PST] tune toctree-related styles #28408
• DOC [PST] better integrate gallery with pydata-sphinx-theme #28415
• DOC [PST] refactor API structure and improve display #28428
• DOC [PST] tune FAQ page styling #28448
• DOC add Algolia search bar for improved website search #28478
• DOC [PST] use jinja2 template for rst generation #28511
• DOC [PST] disable gallery link tweaks when html-noplot to avoid warnings #28512
• DOC [PST] fix styling/simplify structure of testimonial and about pages #28623
• DOC [PST] FIX/RFC machine learning map #28630
• Fix admonitions (Todo: make e.g. .. note:: something into .. admonition:: something with :class: note)

Tracking work related by towards the main branch

• MAINT remove unneeded robots.txt #28387
• MAINT create robots.txt for setting up pydata-sphinx-theme preview #28376
• DOC fix a sphinx warning and a rendering issue #28315
• DOC nitpicks on the FAQ page #28272
• DOC fix some hooks that fail to capture the titles in pydata-sphinx-theme setup #28271
• DOC restructure changelog (in particular for switching to pydata-sphinx-theme) #28255
• DOC solve some sphinx errors when updating to pydata-sphinx-theme #28134
• DOC fix wrong indentations in the documentation that lead to undesired blockquotes #28107