A core JavaScript liquid layout function that checks the current width of a browser window and assigns a new class to the BODY accordingly.

Liquid Layout - Change Classes Based on Width of Browser Window

//LIQUID LAYOUT
function setScreenClass(){
    var fmt = document.documentElement.clientWidth;
    var cls = (fmt>640&&fmt<=800)?'screen_low':(fmt>800&&fmt<=1024)?'screen_med':(fmt>1024&&fmt<=1280)?'screen_high':(fmt>1280)?'screen_wide':'screen_low';
    document.body.className=cls;
};