Are you talking about the space on top and bottom of the inner content? If so, you can reduce the top and bottom padding by adding this –
.front-page-12 .flexible-widgets {
padding: 80px 0 60px;
}
You can adjust those however you want it to look. The 80px covers the top, and the 60px covers the bottom.
The button already seems to be aligned in the middle, did you get that fixed already or where you referring to something else?
