> > > 4. Why isn't the dialog horizontally centered in the viewport? The spec > > just mentions vertical centering and 'top'. >
> The horizontal centering is done via the default CSS. The vertical > centering can't be done with CSS, hence all the prose about it. That isn't true anymore. There are a few very reliable techniques, such as flexbox or a combination of display: inline-block and vertical-align: middle.
