I don’t know what you’re proposing, but I found this article that seems to say that responsive ads can ignore their containers now.
…responsive ad units can now resize the HTML parent container (e.g.
<div>) that they’re within. This allows them to automatically adapt to all the different ad sizes on publishers’ pages.Note that for responsive ad units to work properly, they must not be placed inside a container with a fixed or limited height.
Cool. 
If you want to limit the height of your responsive ads, you’ll need to modify your responsive ad code…
<ins class="adsbygoogle" style="display:inline-block;min-width:400px;max-width:970px;width:100%;height:90px"
So do the same thing as the way it worked before with containers and css, but do it with inline styles instead to let Google “automatically adapt to all the different ad sizes” whatever that means.
BUT their examples show that using CSS should still work: @ljpp see this article:
Are you sure you haven’t tried using CSS to control the max width/height of the responsive units? The two articles contradict each other, so maybe their examples are obsolete.