Hi,

This issue is solved in the website repository now. The following 
commits fix remaining validation errors related to the use of the 
obsolete TT element:

  * 13a1a5a41df9eae7d3ca54c6ab4774c7804dba45
    <https://git.savannah.gnu.org/cgit/guix/guix-artwork.git/commit/?id=38ba9baa9162e4060160c03d0827787c9f52e26c>
  * 38ba9baa9162e4060160c03d0827787c9f52e26c
    <https://git.savannah.gnu.org/cgit/guix/guix-artwork.git/commit/?id=38ba9baa9162e4060160c03d0827787c9f52e26c>

And the following commit fixes a validation error related to using a P 
element as a container of DIV elements:

b951df49798db870aab5ebd4c63d70d2d0c6c8cf 
<https://git.savannah.gnu.org/cgit/guix/guix-artwork.git/commit/?id=b951df49798db870aab5ebd4c63d70d2d0c6c8cf>

I think once these changes are deployed to gnu.org and guix.info this 
issue can be closed.

P. S.: I would deploy it myself, but I don't remember how to do it in 
the case of gnu.org, and I don't have information about guix.info.

:)