Funny business with wordpress headers - help greatly recieved :)

Hi All,

I am working on the following website and the headers are running up into the navigation.
Does anyone know why this is happening? It might alse be worth mentioning that this could also just be the CSS!

http://www.camargueholidayvilla.com/activities/

This is the code in the header.php

<!DOCTYPE html>
<html <?php language_attributes(); ?>>
<head>
<meta http-equiv="content-type" content="<?php bloginfo('html_type'); ?>; charset=<?php bloginfo('charset'); ?>" />
<title><?php wp_title(' | ', true, 'right'); ?></title>
<link rel="stylesheet" type="text/css" href="<?php echo get_stylesheet_uri(); ?>" />
<?php wp_head(); ?>
</head>
<body <?php body_class(); ?>>
<div id="wrapper" class="hfeed">
<header>
<div id="header">
<div id="site-title"><h1><?php if ( is_singular() ) {} else {echo '<h1>';} ?><a href="<?php echo home_url() ?>/" title="<?php bloginfo( 'name' ) ?>" rel="home"><?php bloginfo( 'name' ) ?></a><?php if ( is_singular() ) {} else {echo '</h1>';} ?></h1></div>
<h2 id="site-description"><?php bloginfo( 'description' ) ?></h2>


</header>
</div>
<div id="page-wrap">

<div id="nav">
<?php get_search_form(); ?>
</div>
<?php wp_nav_menu( array( 'theme_location' => 'main-menu' ) ); ?>
</h2>


</header>
</div>
<div id="page-wrap">

<div id="nav">
<?php get_search_form(); ?>
</div>
<?php wp_nav_menu( array( 'theme_location' => 'main-menu' ) ); ?>



<?php get_header(); ?>
<div id="content">
<?php the_post(); ?>
<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
<h2 class="entry-title"><?php the_title(); ?></h2>
<div class="entry-content">
<?php
if ( has_post_thumbnail() ) {
the_post_thumbnail();
}
?>
<?php the_content(); ?>

</div>
</div>

</div>
<?php get_footer(); ?>


<div class="clear"></div>
</div>
<footer>
</footer>
</div>
<?php wp_footer(); ?>
</body>
</html>