更改默认的jQueryUI类如下：

Change the default jQueryUI class like this:

.ui-widget-overlay { 
    background: #aaaaaa url(images/ui-bg_flat_0_aaaaaa_40x100.png) 50% 50% repeat-x !important;
    opacity: 100 !important;
    filter:Alpha(Opacity=100) !important;  
}

只需将颜色和不透明度更改为您喜欢的颜色，这将适用于模态打开时的页面。

Just change the color and opacity to what you like and this will be applied to the page when the modal opens.

如果！important 不起作用，则说明设置有问题。

If the !important don't work you have an issue with your setup.

也许你没有jQueryUI全功能。确保在元素中链接/引用了jQueryUI js和css文件。

Maybe you don't have jQueryUI fully functional. Make sure you have both the jQueryUI js and css files linked/referenced in your element.