function toggle_page_nav(submenu) {
	if (document.getElementById('page_nav' + submenu).style.display == 'none') {
		document.getElementById('page_nav' + submenu).style.display = 'block';
		document.getElementById('page_nav_img' + submenu).className = 'site_page_nav_cont_rub_ouvert';
	} else {
		document.getElementById('page_nav' + submenu).style.display = 'none';
		document.getElementById('page_nav_img' + submenu).className = 'site_page_nav_cont_rub_ferme';
	}
}