function showNav( nav_content_id ) {
	//alert("nav_content_id: " + nav_content_id);
	
	// Swap the visibility of the subnav itself
	if( nav_content_id == 'home' || nav_content_id == 'contact' ) {
		document.getElementById('sub-navs-hide').style.display = "block";
		document.getElementById('sub-navs').style.display = "none";
	} else {
		document.getElementById('sub-navs').style.display = "block";
		document.getElementById('sub-navs-hide').style.display = "none";
	}

	// get a list of all the child elements in the tab_container
	var nav_contents = document.getElementById("sub-nav-container").childNodes;

	for(var i=0; i < nav_contents.length; i++) {
		var content = nav_contents[i];

		//skip all children that aren't tab_content elements
		if( content.className == "sub-nav-content" ) {
			//alert("content.id: " + content.id + ", className: " + content.className);
			// if this is the one we want to show, show it, hide others
			if( content.id == (nav_content_id + '-subnav')) {
				content.style.display = "block";
			} else {
				content.style.display = "none";
			}
		}
	}
}