Make iframe Fabric-based styles consistent with new Fabric layout
Note that this also affects the HTML cloud macros as they are also in an iframe. See HTML-107.
As a user, I want my Fast Multiexcerpt macro styles to look similar to the Fabric or non-Fabric page the macro is in.
Some changes were made to align with new Fabric fonts a while back. However, they reverted the fonts again to be closer to what the legacy pages use.
The result is that our font overrides look out of place in both page types. We need to remove those overrides, see how content in the iframes look in both kinds of pages, then see if we need to put some other override in instead. Note that we do not know what context the macro is in: Fabric or non-Fabric.