JQuery gives different values for window height each time i refresh the page

Question

why does it return 671 when i first time load the page with google chrome but it returns different value when i relad the page

$("#online").css({height: $(window).height()-40-$("#head").height()});

Answer 1

Try setting up the layout on load and resize

$(window).on("load resize", function (e) {
    $("#online").css({height: $(window).height()-40-$("#head").height()});
});

Answer 2

Fiddle

$("#online").css({ height: $(window).height() - 40 - $("#head").height() +'px' });