The below CSS should do it:
media="all"
hr {
border: none;
}
This will affect the hr
element, its full CSS currently is:
hr {
border: none; /* setting this to none removes the line */
border-width: 1px 0 0;
clear: both;
margin: 30px 0 30px 0;
height: 0;
}
If you also want to remove the border under the header, also change
media="all"
.navibg {
background: url(images/whitebg.png);
border-bottom: none;
}