My background isn't spanning horizontally

My background isn't spanning horizontally

I have this code, the only code on the site that would be affecting the
background. I had Eric Meyer's CSS reset on, but commented it out to see.
It made no difference. The only code I have left is this.
* {
margin: 0;
padding: 0;
}
body {
background: url("../images/bg.png") no-repeat center center fixed;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}
I tried many different things to get it to touch the side of the browsers,
but there remains an annoying margin or something on the sides. Any ideas
on how to get rid of this?
Here's what it looks like: