Try replacing your
.menu_section li a CSS block with these two, so that <a> isn't treated as yet another block.
Code:
.menu_section li {
display: block;
padding: 5px;
background-color: #cfcfcf;
margin: 0 0 1px 0;
}
.menu_section li a {
color: #fff;
text-decoration: none;
}
(by the way, this change is tested.)
[ edit: if you really really wanted the text in the .description text to be raised, add a smaller line-height (say, 1em) to the .description section ]