function toggle3D() {
  var threedElements=jQuery(".threed");
  var nonthreedElements=jQuery(".nonthreed");
  if(threedElements.size() > 0) {
    threedElements.addClass("nonthreed");
    threedElements.removeClass("threed");
  } else if(nonthreedElements.size() > 0) {
    nonthreedElements.addClass("threed");
    nonthreedElements.removeClass("nonthreed");
  }
}

function toggleAbrams() {
  var abramsElements = jQuery(".abrams");
  var nonabramsElements = jQuery(".nonabrams");
  if(abramsElements.size() > 0) {
    abramsElements.addClass("nonabrams");
    abramsElements.removeClass("abrams");
  } else if(nonabramsElements.size() > 0) {
    nonabramsElements.addClass("abrams");
    nonabramsElements.removeClass("nonabrams");
  }
}

function toggleSidebar() {
  var sidebarElement = jQuery("#rightnav");
  if(sidebarElement.size() > 0) {
    if(sidebarElement.hasClass("pinned")) {
      sidebarElement.removeClass("pinned");
    } else {
      sidebarElement.addClass("pinned");
    }
  }
}