top margin problem

Got an issue.

I wanted the top margin on my page (twenty eleven theme) to be removed. So I searched.
I tried bringing the margin down, but that didn’t seem to work. To be sure I increased the margin from 2em to 5em and guess what? It worked.

I knew I had the right code now. But now there is the problem. The margin is now stuck on 5em. I can’t decrease it. I changed it to 1em and although it is changed in the code and it stays changed, the site still shows the large margin of 5em.

So problem? Margin doesn’t decreas. What do I do?

What have I already done?
Renewed the page ctrl+f5
I removed all the history and cache from my browsers.
I closed the browsers and started over.
Used a different kind of browser to see if the problem was only part of the browser I was working with.