Question: I'm not sure if I should be using `overflow` or something else to fix this, but would appreciate any help I could get.

Scroll to the very bottom of the page. You will see at the very bottom where there's the black div and right below that is a little white space.

How can make that white space become black and still keep the rounded corners?

Answer: 
You have to set your padding-bottom to 0, and set the border radius bottom to the right and the left of the s-in-mid div.
in signup.css line 293 change #fff to #000, as below, tested in chrome.

```
.s-inn-mid {
width: 1000px;
margin: 0;
padding: 7px 0px 6px 0px;
float: left;
background: none repeat scroll 0 0 #000;  
border: 1px solid #CCCCCC;
box-shadow: 0 0 2px rgba(0, 0, 0, 0.1);
border-radius: 5px;
-moz-border-radius: 5px;
-webkit-border-radius: 5px;
}

```