The 404 page for the Carthage site includes a default header image, a search box to encourage the user to search for what they’re looking for, and (optionally) a list of pages that might resemble the desired page URL.

There’s also an area for customized content, in case you’d like to add additional content or other information. That content can be entered by editing this page and changing the custom-404-content editable area below this one.