What: Currently, skip to content link sends users to an in-page anchor that sits alongside the main page content container. This generally has the desired effect for sighted keyboard users, however, for screen reader users (SRU) this basically leads to a dead end. It's a dead-end in that the target anchor doesn't contain the page content, so nothing further is announced after the element has been focused.

I think what would be better is if we allow the main content container to carry an id, which can be used as the target of the SkipToContent component. Doing this along with supplying a tabindex="-1" for the main content area gives us a solid hook for informing SRU of general route changes and informing them of what content is now available.

For sighted users, I don't think this will cause any difference in behavior (we may want to add a style like outline: none to the primary page container, although I don't recommend this.

Additional issues: #2591

These changes are driven by a technique suggested in https://dequeuniversity.com where in response to dynamic content changes (like navigating to a new "Page" in a SPA) we want to send focus to the new content so that it is announced and SRU receive some feedback about the new content.