There was a remaining issue when the window was made very narrow in
desktop mode (smaller than 500px). This patch doesn't aim to really
"fix" the dialog's design in this case. The goal is to make the popup
window appear less broken, so the text can stil be read and the
buttons clicked. That's all.
This patch should not have any effect in:
a) mobile mode,
b) desktop mode when the window is wider than 500px.
Bug: T294839
Change-Id: I3171dbb991533b91eaadba63b78d0ff40aa486dc
