Modifying padding on the edges of a page

Site URL: https://www.mollycoffin.com

Hi, I'm trying to figure out how to reduce the amount of padding along the edges of my site. Does anyone know how to do that, preferably without getting into any HTML? I'm looking to reduce the width to about a third of what's pictured below, so the image and form scale up a little with the responsive theme and fill the page more. Thanks!

The page has a limit of 680px

You can add this CSS to increase limit

section#contact>div {
    max-width: 900px;
}