I fount the following code to generate random sentences. It work great and I injected the code into my page. However I would like to be able to format the text generated by the script without affecting the format of the remaining parts of my page. Probably this is very easy to do but I am very new at this and was not able to find the way to format only this specific block.
Many thanks in advance for any help.

<title>Random Text</title>
<script type="text/javascript">
var textarray = [
"sentence 1",
"sentence 2",
"sentence 3",
"sentence 4" // No comma after last entry

function RndText() {
var rannum= Math.floor(Math.random()*textarray.length);
onload = function() { RndText(); }

var inter = setInterval(function() { RndText(); }, 2000);

<div id="ShowText"></div>