Move header nav menu down

I’d like help removing the main nav bar in my GDF site down because it’s hiding the top banner.

Here’s the code in WP admin > GDF Options > Quick code:

#header{
margin: 0 auto;
}

#site-title, #site-description {
display: none;
}

.header {
background-color: transparent;
background-image: url(“http://www.mysite.com/wp-content/themes/gdf/images/banner.png”);
}

header nav {
background-color: #1ecaed;
background-repeat: no-repeat;
position:relative;
}
header nav .nav li a, header nav .nav li a:hover {
line-height: 16px;
color: #fff;
}