That white space is actually the Body background (which can be found around line 154). The front-page-2 widget is only 1000px wide, and the orange you see covers the entire area of the fp2 widget. Since the fp2 widget is pushed up with margin-top: 160px;
the only thing that can show on the sides of that area is the body background color.
You can try changing the body background on the homepage itself to make it match the widget you’re using under it by adding something like this –
body.home {
background-color: #fffcf7;
}
You’ll have to either adjust the color of the body, or adjust the background image in the widget below fp2 in order to get it to match perfectly.