This custom CSS code works with any Elegant Themes theme. It can be used to make footer stick to the bottom of the screen.

When logged into WordPress navigate to Divi >> Theme Options and in the custom CSS box at the bottom, place the following code:

#main-footer {
position:fixed;
left:0px;
bottom:0px;
height:50px;
width:100%;
z-index: 9999;
}