I have a site on which I use several divs with one class, which are displayed, and severals divs with an other class which are hidden. 

I would then like to have two buttons, which I can use to toggle between which one of the two classes are displayed, with the button for the currently displayed class beeing inactive.

When the button is clicked I would like it to take effect all through the site, so the correct class is also displayed or hidden on other pages on the site.

To simplify:
So if I click button A, class A is displayed all through the site, and button B is hidden. If I then click button B, class B is displayed all through the site, and button A is hidden.

Any ideas to an easy solution for this?