align attribute seems ignored in HTML and PDF rendering of artwork align="center"

[alicerusso]

In RFC 9251 (e.g., Section 9.1), XML contains artwork align="center" but the output has it left-aligned in PDF and HTML. (It's as expected in the text output.) See the first and second artworks in S9.1:
https://www.rfc-editor.org/rfc/rfc9251.html#section-9.1
https://www.rfc-editor.org/rfc/rfc9251.pdf#section-9.1
https://www.rfc-editor.org/rfc/rfc9251.txt

In the prepped XML file (https://www.rfc-editor.org/rfc/rfc9251.xml), they are:

<artwork name="" type="" align="center" alt="" pn="section-9.1-2">   
<artwork name="" type="" align="center" alt="" pn="section-9.1-4">

Guessing that it's supposed to yield the same alignment in all 3 outputs. (Here's the documentation for ''align''.)

Another example: see artwork in Section 3.3.4 of RFC 9260:
https://www.rfc-editor.org/rfc/rfc9260.html#section-3.3.4-7.16.3 (left aligned)
vs. https://www.rfc-editor.org/rfc/rfc9260.txt (centered, as expected)
(This issue occurs with other artwork elements within that document, but it's more obvious when the artwork is narrow.)

Perhaps this issue only occurs when <artwork> is not within <figure> bc there are examples where the 3 outputs match (when XML contains artwork align="center"), e.g., Figure 1 in https://www.rfc-editor.org/rfc/rfc9174.html, Figure 1 in https://www.rfc-editor.org/rfc/rfc9125.html, Figure 1 in https://www.rfc-editor.org/rfc/rfc9182.html.

[kesara]

This is caused by #788 and this occurs regardless of <figure> is present as a parent element.
Removal of display: table; from .alignCenter > *:first-child in CSS is causing this issue.

[kesara]

Looks like new Weasyprint versions will play nicely with display: table.
I will revert this CSS style back to display: table when Weasyprint update (#802) is complete.
Reverting back should fix both this issue and #787.

[martinthomson]

It is possible that the right answer here is to use flexbox layout for figures, which would allow for better placement. No idea if weasyprint is able to handle that though.