function show_case_studies() {

a = document.getElementById("case_studies_navigation");
b = document.getElementById("case_studies_link");

if (a.style.display == 'block')
	{
	a.style.display = 'none';
	b.className = 'left_link';
	}
else
	{
	a.style.display = 'block';
	b.className = 'left_link_dark';
	}

}