Yes, I looked at my code in a letter to gmail - my <style> styles are not there, and neither is the svg - the mail deletes everything. I tried the inliner method - it is not possible to register selectors with this method - here is the result
https://prnt.sc/xr35rv .
Maybe there are super services for inliner - if anyone knows, throw it!
In general, I assume that inliner will not help.
What other options are there? We now have 4 languages and will have two more - a total of six. If you write in 6 languages in a line and send such a letter to a client, it's a shame for us to the delight of our competitors!
A decision is needed, are we alone using several languages.
PS. my code is here
https://jsfiddle.net/web123/L7ksrue4/2/