Ok, I got it. The problem becuase my theme is using an old version of jQuery.
How to fix?
To edit jQuery version in Function.php (Theme function).
Thank you very much for your help
First.
I got a problem like @newuser2. In my opinion, if we don’t use ‘theme CSS stylesheet in HTML’. A simple HTML in Email Template should be working fine.
Could you suggest me How to fix it without use ‘theme CSS stylesheet in HTML’?
