Dialogs are now better constrained on the screen, with maximum widths

for standard dialog sizes that keep it from reaching to the full width

of the viewport:


Fit dialogs are now a minimum of 35vw (viewport width) and max of

  60vw, with a maximum height of 60vh (viewport height).


Medium dialogs are now a minimum of 60vw and 60vh, and a maximum of

  70vw and 70vh.


Large dialogs are now a minimum and maximum of 80vw and 80vh.


The minimum/maximum widths for Fit and Medium allow for some growth if

the content requires.
The dialog's body is also now set to show scrollbars if needed. This

avoids the scrollbar that would otherwise be placed on the <dialog>,

which covered the title and buttons area.

Tested all the dialog sizes with minimum and maximum sizes, using

a variety of test content.