#3 How to output relative path to root from template

[Rory]

How do I specify the relative path to the root directory
from within a template? eg is there a function (or
curator tag) that will return '../' when called for a
subdirectory of root and will return '' when called for
root?

What I want is to have a single stylesheet file for my
curator-generated pages. So I want to have a tag
calling a function something like this in my template
files:

<link href="<!--pathToRootDirectory-->curator.css"
rel="stylesheet" type="text/css" >

where "pathToRootDirectory" returns the appropriate ../
or ../../ etc.

any suggestions?

many thanks,

- Rory