function changeText(num) {

   if (num == 1) {
        var oP = document.getElementsByTagName('p');//the collection of <p> tags
        for (var i = 0; i < oP.length; i++) { oP[i].style.fontSize = '12px'; oP[i].style.lineHeight = '17px'; }

        var oP = document.getElementsByTagName('li');//the collection of <li> tags
        for (var i = 0; i < oP.length; i++) { oP[i].style.fontSize = '12px'; oP[i].style.lineHeight = '20px'; }

        var oP = document.getElementsByTagName('h1');//the collection of <h1> tags
        for (var i = 0; i < oP.length; i++) { oP[i].style.fontSize = '18px'; oP[i].style.lineHeight = '36px'; }
    }

   if (num == 2) {
        var oP = document.getElementsByTagName('p');//the collection of <p> tags
        for (var i = 0; i < oP.length; i++) { oP[i].style.fontSize = '14px'; oP[i].style.lineHeight = '19px'; }

        var oP = document.getElementsByTagName('li');//the collection of <li> tags
        for (var i = 0; i < oP.length; i++) { oP[i].style.fontSize = '14px'; oP[i].style.lineHeight = '19px'; }

        var oP = document.getElementsByTagName('h1');//the collection of <h1> tags
        for (var i = 0; i < oP.length; i++) { oP[i].style.fontSize = '20px'; oP[i].style.lineHeight = '36px'; }
    }

   if (num == 3) {
        var oP = document.getElementsByTagName('p');//the collection of <p> tags
        for (var i = 0; i < oP.length; i++) { oP[i].style.fontSize = '16px'; oP[i].style.lineHeight = '21px'; }

        var oP = document.getElementsByTagName('li');//the collection of <li> tags
        for (var i = 0; i < oP.length; i++) { oP[i].style.fontSize = '16px'; oP[i].style.lineHeight = '21px'; }

        var oP = document.getElementsByTagName('h1');//the collection of <h1> tags
        for (var i = 0; i < oP.length; i++) { oP[i].style.fontSize = '22px'; oP[i].style.lineHeight = '36px'; }
    }



}