yes you can !!
if you know anything about html and css is easly done by adding a div tag in your descripting textarea and give it the propper css values ...
css would be
#hidenav {
border: none;
width: 100%;
display: block;
background: #000000;
height: 45px;
position: absolute;
top: 0px;
left: 0px;
z-index: 1;
overflow: hidden;
}
and in your description
<div ID="hidenav"></div>
and ofcource give the background color in the css the same values as the background of your website..
use this code at your own risk because it is not supported by pbase and not very pbase friendly ... as users can not switch between galleries nor find the other pbase features and given the hard task in developing and maintaining pbase I advice you not to implement it.
hope it helps