changing page's background color

changing page's background color

Hi all
I have a small script that changes the background color of my page from white to grey when the user clicks a button.
at the moment it works fine accept for when the user tries to navigate to another page (on my website) after changing the background color.
if a user changes the background color to grey and than tries to view another page, the background color becomes white again.
is there any way to make the change only controlled by the button?

my head code looks like this (at least the relevant parts):









+++++++++++++++++++++++++++++++++++++++++++++++++++++++

i have a link with ID=#switch_lnk, which once clicked, changes attributes for 'body' and 'div#side_menu #menu li.active'..

i should add that this website is using Joomla! CMS and that this script is part of the index.php file - meaning it appears on every page in my website.

any ideas?

thank you all so much.