I had the same issue a few years back and found a fix for it. I've tried everything I could think of, but nothing is working.

I have this problem only in the FireFox browser.

For some odd reason I have between 15 and 20 pixel margin (maybe padding) at the very top of the page. I've use firebug to try to solve the issue, but still can't seem to find it.

Here is the site: augrabbernome.com

Any help is appreciated.

its the 15px in this css

div.widget {
    display: block;
    margin: 0 0 15px;
    width: auto;
}

Wouldn't that add a 15px margin below the widget, not above?

div.widget {
    display: block;
    margin: 0 0 15px;
    width: auto;
}

margin: 0 (top margin), 0 (right/left margin), 15px(bottom margin);

Did you try it?

Yes, I did try it. Both in Style Widgets > Widget Container and in Add HTML/CSS Inserts > CSS Inserts

The odd thing is that the problem only shows up in the Firefox browser.

Hmmm...

Any other suggestions?

try this in css inserts and leave it there if it doesn't work so I can take a look

div#text-2 {
    margin: 0 0 0px !important;
}

the reason I'm givine you this code is that when I use FireBug, this is what makes the margin go away.
it is caused by the 'float: Left' you have assigned in the div of the logo.png If you get rid of the float: left the gap goes away, but the image drops down.

I solved the issue, well not really. I just did something completely different for the same result.

First I removed all margins on text-2, I increased the logo image height to 165px for a false 15px margin at the bottom.

Then I added the pile of gold as two background images. The top part goes into the 'logo bar' and the bottom half into the 'navigation bar'. It works great.

I still don't know why I was getting that extra margin at the top, but I found a solution that works.

the reason (as I said) was because of the 'float: left;'. It seems that FireFox does it a bit different than chrome and safari.

But I'm glad you have a solution - I'll make this solved (you can always reopen it if you need to)