var prevPage = null;
var prevContent = null;

// Displays/hides the current/previous content
function content(id) {
  if (!prevContent) prevContent = "main";
  
  document.getElementById(prevContent).style.display = "none";
  prevContent = id;
  document.getElementById(id).style.display = "block";
  
  menu("m"+id);
}


// Changes the classname of the menuitem of the previous page visited. 
function menu(id) {
  if (!prevPage) prevPage = "mmain";
  
  document.getElementById(prevPage).className = "inactive";
  prevPage = id;
  document.getElementById(id).className = "active";
  

}