How do I report a bug against Ubuntu.com (the Ubuntu website)

The ubuntu-website project on Launchpad is the right place. Their remit covers all the Ubuntu.* domain websites.

Whether or not you get any answers is another question. I suggest you post the bug there first and then follow the tip on the contact us page, and contact the webmasters:

Web feedback

If you have suggestions or corrections for ubuntu.com or canonical.com, email us at [email protected] or [email protected].

Edit: I just had a little rummage around. I saw one of your bugs there and if I did triage there I would close that bug. You're using a beta browser. The footer works just fine in Firefox 3.6 and the latest chromium. The bug is therefore most likely in Firefox and you should report it to Mozilla, not Ubuntu.

As of 12 April 2016, the aforementioned canonical (lowercase c) website project on Launchpad was rendered obsolete, as one can see from its name ("Ubuntu Website - OBSOLETE") and its description:

OLD PROJECT - OBSOLETE AS OF 12 APRIL 2016

The new description also points to the new location for development and bug reporting as it relates to the website:

The ubuntu.com website project - PLEASE FILE BUGS HERE INSTEAD: https://github.com/ubuntudesign/www.ubuntu.com/issues/new

Additionally, there's a footer at the bottom of every page on ubuntu.com that directs to the right location:

Legal information · Data privacy · Report a bug on this site

That last link leads directly to a bug reporting template on the GitHub project for the website, which is part of the Canonical Web and Design Team.