Is div styling allowed on AMP HTML?

Question

So i was experimenting with AMP and i noticed that

<div style="font-size:xx-small;color:white;"></div>

is accepted as regular AMP. (tested with Google AMP tester)

Now i thought that only amp-custom styling is valid on AMP.

Should i leave div styling or is something strange that AMP tester is not detecting and will make my AMP template invalid latter.

PS. I know that this kind of styling is not appropriate and is better to style by css but just wandering as a rule in principle. Thnx

Answer 1

Yes

First result on Google:

Styles may live in the head of the document or as inline style attributes...