I've used httrack on a site that uses imports on a cascade 
style sheet and it translates the relative url wrong 
(although i'm not sure about the rules in css..)

But the case is in one site: <http://www.ist.utl.pt>.
The <http://www.ist.utl.pt/css/iststyle.css> that is used 
imports a main.css.. like this: @import url("main.css");

This file is located at <http://www.ist.utl.pt/css/main.css> 
and not in <http://www.ist.utl.pt/main.css> as httrack 
translates it.

Just thought you should know.