// JavaScript Document

function phase1On() { 
    blockOn('project-nav1');
    blockOff('project-nav2');
    blockOff('project-nav3');
    swapClass('project-nav-header1','nav-selected'); 
    swapClass('project-nav-header2','nav-not-selected'); 
    swapClass('project-nav-header3','nav-not-selected'); 
} 
function phase2On() { 
    blockOff('project-nav1');
    blockOn('project-nav2');
    blockOff('project-nav3');
    swapClass('project-nav-header1','nav-not-selected'); 
    swapClass('project-nav-header2','nav-selected'); 
    swapClass('project-nav-header3','nav-not-selected'); 
} 
function phase3On() { 
    blockOff('project-nav1');
    blockOff('project-nav2');
    blockOn('project-nav3');
    swapClass('project-nav-header1','nav-not-selected'); 
    swapClass('project-nav-header2','nav-not-selected'); 
    swapClass('project-nav-header3','nav-selected'); 
} 
function blockOn(id){
  if (document.getElementById){
    document.getElementById(id).style.display = 'block';
  } 
}
function blockOff(id){
  if (document.getElementById){
    document.getElementById(id).style.display = 'none';
  } 
}
function swapClass(id, className){
  if (document.getElementById){
    document.getElementById(id).className = className;
  } 
}