Bryon,
You have to correct the following to your my-menu.css:
.center {
align:center
width:402px;
margin: auto;
height: auto;
border: none;
}
This is right under the body declaration. As you will see, the align: center is lacking the ; at the end, which leads to no recognition of the width. Actually, you don't need that line at all, the margin:auto is all you need.
Then further down, below the page styles comment:
.center {
width:604px;
margin: auto;
height: 0px;
border: 0px;
}
This center class has a different width, and as it is coming after the first center class, it will rule out the definitions given above, hence the name 'CASCADING style sheet'. This is the reason for the menu to jeer off the center.
If you need the definitions in the second center class, then call the class something else, if not, delete it.