docs/build/latex/sphinxlatexstylepage.sty

%% PAGE STYLING
%
% change this info string if making any custom modification
\ProvidesPackage{sphinxlatexstylepage}[2021/01/27 page styling]

% Separate paragraphs by space by default.
\RequirePackage{parskip}

% Style parameters and macros used by most documents here
\raggedbottom
\sloppy
\hbadness = 5000                % don't print trivial gripes

% Require package fancyhdr except under memoir class
\@ifclassloaded{memoir}{}{\RequirePackage{fancyhdr}}
% Use \pagestyle{normal} as the primary pagestyle for text.
% Redefine the 'normal' header/footer style when using "fancyhdr" package:
\@ifpackageloaded{fancyhdr}{%
  \ltx@ifundefined{c@chapter}
  {% no \chapter, "howto" (non-Japanese) docclass
   \fancypagestyle{plain}{
    \fancyhf{}
    \fancyfoot[C]{{\py@HeaderFamily\thepage}}
    \renewcommand{\headrulewidth}{0pt}
    \renewcommand{\footrulewidth}{0pt}
   }
   % Same as 'plain', this way we can use it in template
   % FIXME: shouldn't this have a running header with Name and Release like 'manual'?
   \fancypagestyle{normal}{
    \fancyhf{}
    \fancyfoot[C]{{\py@HeaderFamily\thepage}}
    \renewcommand{\headrulewidth}{0pt}
    \renewcommand{\footrulewidth}{0pt}
   }
  }%
  {% classes with \chapter command
   \fancypagestyle{normal}{
    \fancyhf{}
    \fancyfoot[RO]{{\py@HeaderFamily\thepage}}
    \fancyfoot[LO]{{\py@HeaderFamily\nouppercase{\rightmark}}}
    \fancyhead[RO]{{\py@HeaderFamily \@title\sphinxheadercomma\py@release}}
    \if@twoside
     \fancyfoot[LE]{{\py@HeaderFamily\thepage}}
     \fancyfoot[RE]{{\py@HeaderFamily\nouppercase{\leftmark}}}
     \fancyhead[LE]{{\py@HeaderFamily \@title\sphinxheadercomma\py@release}}
    \fi
    \renewcommand{\headrulewidth}{0.4pt}
    \renewcommand{\footrulewidth}{0.4pt}
    % define chaptermark with \@chappos when \@chappos is available for Japanese
    \ltx@ifundefined{@chappos}{}
      {\def\chaptermark##1{\markboth{\@chapapp\space\thechapter\space\@chappos\space ##1}{}}}
    }
  % Update the plain style so we get the page number & footer line,
  % but not a chapter or section title.  This is to keep the first
  % page of a chapter `clean.'
   \fancypagestyle{plain}{
    \fancyhf{}
    \fancyfoot[RO]{{\py@HeaderFamily\thepage}}
    \if@twoside\fancyfoot[LE]{{\py@HeaderFamily\thepage}}\fi
    \renewcommand{\headrulewidth}{0pt}
    \renewcommand{\footrulewidth}{0.4pt}
    }
   }
  }
  {% no fancyhdr: memoir class
   % Provide default for 'normal' style simply as an alias of 'plain' style
   % This way we can use \pagestyle{normal} in LaTeX template
   \def\ps@normal{\ps@plain}
   % Users of memoir class are invited to redefine 'normal' style in preamble
  }


\endinput