its not your domain. its your web server.
You probably can get it to rewrite that, but if it is hosted you'll have to ask how to do that.
You only need to forward the unadorned one to /dr, and after that it would work fine.
Update:
So if it is hosted, that might their convention. If you installed it, then your pathing is wrong.
In any event, a rewrite rule or meta refresh call can put the initial web access into the /dir/ directory.
If it can run without the /dir/ (you didn't embed the path your code). then moving and setting the correct directory root will work (Apache term).