Maybe it's just iframes that are the issue but they were a devil and a half to get working in chrome (or blink ig) without relying on third party cookies.
Interested in what you are doing with the iframes. Something with complex authentication? I've been forced to use iframes a few times for 3rd party resources that should have been first-party (mostly with banks and credit unions), and have only had some styling issues on mobile (which have been overcome by using JavaScript and window.matchMedia to check for media queries).