visibility:hidden/visible 设置为隐藏/显示(始终占位)
display:none/block 设置为隐藏(不占位)/显示(不占位)
$('#divMain').css("visibility", "hidden");
$('#divMain').css("visibility", "visible");
visibility:hidden/visible 设置为隐藏/显示(始终占位)
display:none/block 设置为隐藏(不占位)/显示(不占位)
$('#divMain').css("visibility", "hidden");
$('#divMain').css("visibility", "visible");