manual backport of #25988 to v1.20
- Tell the renderer to use the `document` mode, so it's consistent with
other renderers.
- Use the same padding as `.file-view.markup`, so it's consistent with
other containers that contain markup rendering.
- Resolves https://codeberg.org/forgejo/forgejo/issues/833
Co-authored-by: Earl Warren <109468362+earl-warren@users.noreply.github.com>