function changeMode(mode) { 
    // Toggle visibility between none and block 
  if (mode == 'flash') {
    document.getElementById("flashContent").style.display = 'block';
    document.getElementById("flashMode").style.display = 'none';
    document.getElementById("homeContent").style.display = 'none';
    document.getElementById("HTMLmode").style.display = 'block';
    document.getElementById("menu").style.display = 'none';
    document.getElementById("menu2").style.display = 'none';
  } else if (mode == 'HTML') { 
    document.getElementById("flashContent").style.display = 'none';
    document.getElementById("flashMode").style.display = 'block';
    document.getElementById("homeContent").style.display = 'block';
    document.getElementById("HTMLmode").style.display = 'none';
    document.getElementById("menu").style.display = 'block';
    document.getElementById("menu2").style.display = 'block';
  } 
}