var currentDisplayPage = "displayPage1";
var currentPageNumber = "pageNumber1";

function switchPage(pageNumber, displayPage, selectedCss, newCss){
    var oldDisplayPage = document.getElementById(currentDisplayPage);
    var newDisplayPage = document.getElementById(displayPage);
    
    oldDisplayPage.style.display = 'none';
    newDisplayPage.style.display = '';
    
    document.getElementById(currentPageNumber).className = newCss;
    document.getElementById(pageNumber).className = selectedCss;
    
    currentDisplayPage = displayPage;
    currentPageNumber = pageNumber;
}