open your stylsheet.css , you need to add one rule and modify few rules to set your positions as you have used absolute position in many places.

add this rule to end of your stylesheet.css
#logo {
margin-top : -13px;
}

find following rules and modify the red properties / values

#navigation {
background-image:url(../images/navigation.jpg);
height:45px;
left:200px;
position:absolute;
top:12px; Remove this line
width:650px;
}

#navMainWrapper {
-moz-background-clip:border;
-moz-background-inline-policy:continuous;
-moz-background-originadding;
background:#3B5323 none repeat scroll 0 0;
height:25px;
left:200px;
padding-right:20px;
position:absolute;
top:56px; Change to 45px
width:630px;
}

this is the best i could come up with hope it helps.