function doNav(isDesign,isIllustration,isShop,isContact) {
    $('nav_design').src = 'images/layout/design_' + (isDesign ? 'on' : 'off') + '.jpg';
    $('nav_illustration').src = 'images/layout/illustration_' + (isIllustration ? 'on' : 'off') + '.jpg';
    //$('nav_shop').src = 'images/layout/shop_' + (isShop ? 'on' : 'off') + '.jpg';
    $('nav_contact').src = 'images/layout/contact_' + (isContact ? 'on' : 'off') + '.jpg';

    //sublinks
    //$('nav_design_sub').style.display = isDesign ? '' : 'none';
    //$('nav_illustration_sub').style.display = isIllustration ? '' : 'none';
}