In .htaccess, I have put a simple RewriteRule with two GET variables in the URL:
RewriteRule ^myurl/([0-9a-zA-Z]+)/([0-9a-zA-Z]+) /folder_1/myfile.php?a=$1&b=$2
Inside folder_1, there are two files: myfile.php and myCSS.css
In myfile.php, when I am having to refer to myCSS.css, I am having to do:
<link href="../../folder_1/myCSS.css" rel="stylesheet">
The ../../ is needed to get past the two GET variables set above.
But surely, there must be a better way, as I should be able to add more GET variables and not having to change the relative URL to the CSS each time.