Extending Header Image

Hello,

I am trying to set up a full page header for the site: https://www.dusers.drexel.edu/~aphio/

Unfortunately, the theme was designed to have an ad where I want to extend the logo image. The space is 80×960 and my image is only 80×800.

Heres the header.php info:
<div id=”header”>

<div class=”headerleft”>
/”><img src=”<?php bloginfo(‘template_url’); ?>/images/logo.png” alt=”<?php bloginfo(‘name’); ?>” />
</div>

<!–To define the 468×60 ad, go to your WP dashboard and go to Appearance -> Options and enter the ad code.–>

<div class=”headerright”>
<?php $ad_468 = get_option(‘s_ad_468’); echo stripslashes($ad_468); ?>
</div>

Here’s the CSS info:

#header {
width: 960px;
height: 80px;
color: #FFFFFF;
font-size: 16px;
font-weight: normal;
margin: 0px auto 0px;
padding: 0px;
overflow: hidden;
}

How can I fix this and use the whole space? Thanks for your help.