You can inspect the dialog element with dev tools and see what classes are applied on mdDialog.
For example, .md-dialog-container
is the main classe of the MDDialog and has padding: 24px
you can create a custom CSS to overwrite whatever you want
.md-dialog-container {
background-color: #000;
width: 250px;
height: 250px
}
In my opinion this is not a good option and probably goes against Material guide but since it doesn't have all features it has in it's previous version, you should do what you think is best for you.