There are a couple ways to do this. Most of the space is coming from the content title area. You can remove this by adjusting the code on line 2295 in your style.css file –
.entry {
background: #fff;
margin: 0 3px 40px;
padding: 40px 0 0;
}
If you change the top padding to either 20px, 0 (or whatever you prefer) it will decrease the space you see in between.
Try this first and see how it looks (0px)-
.entry {
background: #fff;
margin: 0 3px 40px;
padding: 0;
}
If that is too much, then you can try this (10px) –
.entry {
background: #fff;
margin: 0 3px 40px;
padding: 10px 0 0;
}