In #33601, the furo theme has been introduced for the documentation. The aim of this ticket is to make it the standard theme. Before it happens, the remaining issues need to be fixed:

• Index page in double columns look awful -- fixed in Make index page single column #34265
• sage logo in the side bar should link to the top of the Sage manuals - fixed in Revive furo #34252
• no link to the doc root - fixed in Add a Home link to the doc root #34267
• search page not working - fixed in Revive furo #34252
• "ERROR: Adding a table of contents in Furo-based documentation is unnecessary" - https://73e5aa3fbbec2d751a47064c14479fc0d55c3de9--sagemath-tobias.netlify.app/installation/source.html#installation-in-a-multiuser-environment - fixed in Remove toc warnings #34262

To support this ticket, the standard Furo package was accepted by the voting done in

• https://groups.google.com/g/sage-devel/c/VTU_I-ecPlA

along with subsidiary votings in

• https://groups.google.com/g/sage-devel/c/eRh16v5Mz0c
• https://groups.google.com/g/sage-devel/c/rhPECxe128o

Other possible improvements:

• Install sphinx-hoverxref, sphinx-notfound-page (see setuptools documentation, which also uses furo - https://setuptools.pypa.io/en/latest/history.html#documentation-changes)

Depends on #34252
Depends on #34262
Depends on #34265
Depends on #34267
Depends on #34450

CC: @kwankyu @strogdon @haraldschilly @mkoeppe

Component: documentation

Author: Kwankyu Lee, Matthias Koeppe

Branch/Commit: 1f03957

Reviewer: Matthias Koeppe, Kwankyu Lee

Issue created by migration from https://trac.sagemath.org/ticket/33833