function showForms( target ){
    
    var doc1 = document.getElementById('bgDark');
    var doc2 = document.getElementById( target );
    
    var viewportHeight = window.innerHeight
    var documentHeight = document.body.scrollHeight;
    
    $('#bgDark').slideToggle('slow');
    
    $('#' + target).slideToggle(
        'slow',
        function(){
            if( viewportHeight > documentHeight ){
                doc1.style.height = viewportHeight + 140 + 'px';
            }else{
                doc1.style.height = documentHeight + 50 + 'px';
            }
        }
    );
}