Sorry, I thought the first image was of the space between the header and navigation position. It's been a long day... Anyway now that I'm looking at your problem again here's what you can do. It is going to be a little more interesting because the "blank" space is actually made up of some padding and margin. Here we go...
Same file templates/rt_camber/css/template.css. I would take 15px all the way down to 0px.rt-block {
margin: 15px 0;
}
Here is the padding. /libraries/gantry/css/gantry.css..rt-block {
margin-bottom: 10px;
padding: 15px;
position: relative;
}
Change it to this:.rt-block {
margin-bottom: 10px;
padding: 0 15px 15px;
position: relative;
}
Increase the 0 to open up space between the top of Mainbottom and the dividing line above. Increase the last 15px for space on top of the dividing line.