Change one menu item into Image

I am having a little difficulty turning one menu item in the main navigation into an image. The reason for doing so is to make the logo the link back to the homepage. Here is the CSS I have been using:

#navigation li #a.menu-item-25 {
background:url(http://127.0.0.1:8080/wordpress/wp-content/uploads/2014/01/Bostin-Irish-Header_Woo.png);
background-position: -240px;
background-repeat: no-repeat;
text-decoration:none;

As you can probably see I am building this site locally so unfortunately I cannot send you guys to a website. I am using the Woothemes Mystile theme: http://www.woothemes.com/products/mystile/

Thanks for your help!