Question

Everything is wrapped in a div with an id="main_wrap"

the main wrap has this style:

#main_wrap{
  margin:0 auto;
  width:960px;
  position:relative;
}

Since everything is wrapped inside of this div, I don’t understand why a horizontal scroll bar would appear at the bottom.

Answer 1

Try add overflow hidden:

#main_wrap{
    margin:0 auto;
    width:960px;
    position:relative;
    overflow: hidden;
}

That should work (but is hacky).