Gap between input form and submit button

Hey guys,

check out this picture from my website: https://f.cl.ly/items/080c3x1e3H2r1G0j3H2G/Screen%20Shot%202014-04-25%20at%207.02.05%20AM.png

There is a big gap between the input form and the submit button. Can I change this? If so, which file to edit?

Thanks!