How to design a CSS for a centered floating confirm dialog?

Question

I\'m looking for a way to display a confirm dialog that\'s always centered on the page, and floating over the page.

Tried that, but it\'s not \'always centered\' at

Answer 1

.Popup
{
width:400px;
margin-left:auto;
margin-right:auto;
}

That's horizontal alignment; vertical alignment is a little trickier. Just Google around for "css vertical center" or something.