Title updation while documentation is generated using STYLE=website

Hi,

While building the documentation with make STYLE=website html, I
noticed inconsistencies in the formatting of the starting letter of
each word in the titles. For instance:
"Obtaining Information about an Error" becomes "Obtaining Information
About An Error" in html/plpgsql-control-structures.html.
"Multiple Statements in a Simple Query" changes to "Multiple
Statements In A Simple Query" in html/protocol-flow.html.
"Returning from a Function" remains unchanged in
html/plpgsql-control-structures.html.
"Obtaining Information about an Error" is also unchanged in
html/plpgsql-control-structures.html.
"RETURN NEXT and RETURN QUERY" changes to "RETURN NEXT And RETURN
QUERY" in html/plpgsql-control-structures.html.

There are many similar cases throughout the code.

I believe this might be related to the stylesheet, as the original
text appears intact when I copy the generated HTML and paste it into
Notepad. I could not get details about this from [1].
How is the styling being applied for the titles? Please share the link
to this if it is available.

[1] - https://www.postgresql.org/docs/current/docguide-build.html

Regards,
Vignesh