about:rulesets semantic and accessibility problems

A few of these issues I noticed:

• The page is missing a <title>.
• The rule list (#ruleset-list) is not focusable and cannot be activated with a keyboard. This element should ideally be a role="listbox" or similar widget with focus management. I don't think it should be part of an <aside> since it is main content, rather than complementary.
• The rule title (#ruleset-title) should probably be <h2> rather than <h1> because it is a section title rather than a page title.
• The use of <dl>, <dt> and <dd> is semantically ok, but I don't think these elements have great screen reader support. Note that the html specification has changed their meaning to be any generic name-value pair https://html.spec.whatwg.org/multipage/grouping-content.html#the-dl-element and the latest ARIA relates these to various "associationlist" roles https://w3c.github.io/aria/#associationlist . But firefox still seems to map to the "definitionlist", "term" and "definition" roles.
• The edit form (#edit-ruleset-form) might benefit from an accessible name. We can probably use aria-labelledby="ruleset-title".