I'm new to this, but this week succeeded with nice code that works with "/?page=2" and stuff for a $_GET[].
For speed and ease I'd been calling my file index.php so the url was either testdomain or testdomain/ or testdomain/?page=2.
Today I changed my filename to multi.php. Now, if anything follows that in the URL, I get an error
"The stylesheet 'http://testdomain/multi.php/mystyle.css' was not loaded because its MIME type, "text/html", is not "text/css".
So URL testdomain/multi.php works perfectly, testdomain/multi.php/ does not.
I've tried as many recommendations about that error as I can find.