data role="page" div height

data role="page" div height

Hello, i have application done with jquery mobile and i want to change page height from default. So far i have tried this (page divs id is mobilepage):
 <script type=\"text/javascript\">
$(document).ready(function(){
                        
                        $('#mobilepage').height(100);
                        //or this
                        $('#mobilepage').css('height','350');
                        alert($('#mobilepage').height());//displays 728

                        })</script>";

Resizing content div like that works, but it doesnt work with page div...why is this and is there any way to resize page div? I need this done because i am running this application in drupal site and if the page is 100% drupal theme looks bad...it needs to be content height.

Thanks in advance, Janne