Going into negatives

I'm having some struggles with finding out which <> I have to use for the following scenario's.

This is part of a website which is going into negatives.

This is the website where it's about: http://ift.tt/1Vlq8z7

As you can see, the first page has a top of 0px, and when you scroll down it goes into negatives. (-635px)

The problem is that I want to put some if statements to each page so it'll be like:

if top 0< {
   do something. 
}

But if it's going down then I'm not sure if I should use > or < on a negative amount of pixels.

Can someone explain to me in which cases I should use > and < ?

Thanks in advance!