always problem with image path!

[eluser]WebbHelp[/eluser]
if somebody don't understand

I got my css file in the same directory as index.php.
Why can't I write the link as only /style.css if they are in same directory?
And how can I do if I got a js file with image paths in? I can't write PHP in there so...

Thanks //WebbHelp

I would be very happy if someone can answer this, actually it is in hurry, sry