// script zum anzeigen und verkstecken von css boxen 

function link() {
  var gross = document.getElementById("link");
  gross.style.visibility = "visible";
  }
function link_off() {
  var gross = document.getElementById("link");
  gross.style.visibility = "hidden";
  
  var gross1 = document.getElementById("link_2");
  gross1.style.visibility = "hidden";
  
  var gross2 = document.getElementById("link_3");
  gross2.style.visibility = "hidden";

  var gross3 = document.getElementById("link_4");
  gross3.style.visibility = "hidden";
  }

function link_2() {
  var gross = document.getElementById("link_2");
  gross.style.visibility = "visible";
  }
function link_2_off() {
  var gross = document.getElementById("link_2");
  gross.style.visibility = "hidden";
  }

function link_3() {
  var gross = document.getElementById("link_3");
  gross.style.visibility = "visible";
  }
function link_3_off() {
  var gross = document.getElementById("link_3");
  gross.style.visibility = "hidden";
  }

function link_4() {
  var gross = document.getElementById("link_4");
  gross.style.visibility = "visible";
  }
function link_4_off() {
  var gross = document.getElementById("link_4");
  gross.style.visibility = "hidden";
  }