Make responsive email template work in Gmail

I have a ready coded responsive email template. It looks and works nicely on desktop and in Apple Mail (perfectly responsive), but for some reason, Gmail just displays the desktop version, even within the Gmail iPhone app. I have tried to make Gmail show the responsive version with help of these hints, but without success: [login to view URL] Attached files: 1. Screenshots for test mail in Apple Mail on iPhone 8 (responsive as expected) 2. Screenshots for test mail in Gmail app on iPhone 8 (showing the desktop version instead of the mobile version) 3. HTML and images for the used template Images in the attached screenshots are just missing because I had not properly uploaded/linked them - there is nothing to fix regarding images. What I'm looking for: a fix to make Gmail also display the responsive version, just like Apple Mail does while making sure that the current design does not break in other clients.