I am getting close to done on the design (I think I change something everyday), but my navigation in FF & IE is fine on a PC. When I view it on a Mac (only when I'm at work :/), it jumps in both FF and Safari. I'm including the header CSS and a link to the page. Any help would be appreciated.

#header {
width: 900px;
height: 254px;
background: url(.../images/header.jpg) no-repeat;
margin: 0 auto;
padding: 0;
}

#header #sitetitle {
width: 350px;
padding-top: 20px;
margin-left: 520px;
font-size: 12px;
}

#header #sitetitle .lrg {
font-size: 16px;
font-weight: bold;
}

#header #nav {
margin: 149px 0 0 10px;
}

#nav a {
display: block;
width: auto;
float: left;
color: #4a4a4a;
margin: 0 5px;
padding: 2px 4px;
font-size: 20px;
text-decoration: none;
border-bottom: 9px solid #d8d8d8;
}

#nav a:hover {
display: block;
width: auto;
float: left;
color: #4a4a4a;
margin: 0 5px;
padding: 2px 4px;
font-size: 20px;
background: none;
text-decoration: none;
border-bottom: 9px solid #bae55e;
}

#nav a .sml {
font-size: 10px;
border: 0;
}

http://www.valuredesign.com