Configuration

mdbook-last-changed is configured using additional options under [output.html]:

[output.html]
# Required: Your repository URL used in the link.
git-repository-url = "https://github.com/$user/$project"

To style the footer add a custom CSS file for your HTML output:

[output.html]
additional-css = ["last-changed.css"]

And in last-changed.css style the <footer> element or directly the CSS element id last-changed:

footer {
  font-size: 0.8em;
  text-align: center;
  border-top: 1px solid black;
  padding: 5px 0;
}

This code block shrinks the text size, center-aligns it under the rest of the content and adds a small horizontal bar above the text to separate it from the page content.

Finally, build your book as normal:

mdbook path/to/book