Some of it is set here:
#s5_top_row2_area2, #s5_top_row3_area2 {
padding-bottom: 50px;
}
template.css (line 1289)
And the rest is set here under the padding of 40px:
.module_round_box {
color: #000000;
margin-left: 7px;
margin-right: 7px;
padding: 40px 0;
text-shadow: none;
}
template.css (line 1025)