The wrapper of the RadAlert/Confirm/Prompt buttons is wider than the dialog itself in Material skin, in IE/Chrome:
https://www.screencast.com/t/4IatOUgMp
  

Steps to reproduce:
1. Open in Chrome: http://demos.telerik.com/aspnet-ajax/window/examples/browserdialogboxes/defaultcs.aspx?skin=Material
2. Click on any of the demo buttons (e.g. RadAlert from Client)

Result: The wrapper of the Dialog buttons is wider than the dialog itself