function getWindowHeight() {
    var windowHeight = 0;
    if (typeof (window.innerHeight) == 'number') {
        windowHeight = window.innerHeight;
    }
    else {
        if (document.documentElement && document.documentElement.clientHeight) {
            windowHeight = document.documentElement.clientHeight;
        }
        else {
            if (document.body && document.body.clientHeight) {
                windowHeight = document.body.clientHeight;
            }
        }
    }
    return windowHeight;
}
function setFooter() {
    if (document.getElementById) {
        var windowHeight = getWindowHeight();

        var contentHeightCentrale = document.getElementById('box_centrale').offsetHeight;
        var contentHeightSx = document.getElementById('box_sx').offsetHeight;
        if (contentHeightCentrale < contentHeightSx) {

            var footerElement = document.getElementById('footer');
            var footerHeight = footerElement.offsetHeight;

            footerElement.style.marginTop = (contentHeightSx - contentHeightCentrale + 200) + 'px';
        }
    }
}
window.onload = function () {
    setFooter();
}