Currently, we apply font inflation calculations to ruby text independently of the calculation for the base text. This means we're liable to inflate the ruby annotation much more than the base, and thereby lose the expected size contrast and mess up the layout. I think that for <rt>, we should inflate only as much as the inflation being applied to the base text, even though this will typically leave the ruby text smaller than the minimum size being applied to normal text in the same inflation container.
Created attachment 8571435 [details] [diff] [review] Reftest for application of font inflation to ruby Here's a reftest that currently fails because we inflate the ruby text independently of its base text.
Created attachment 8571645 [details] [diff] [review] patch
Created attachment 8571646 [details] [diff] [review] patch for reftest Identical to jfkthame's patch, except the order in reftest.list and removal of "fails". Thanks for the great reftest, jfkthame.
Is it really necessary to modify that code, or should you instead be making sure that ruby annotation containers don't end up being a font inflation container?
I don't think ruby annotation containers are ever font inflation container.  (Though some code there doesn't use a proper name.)  https://dxr.mozilla.org/mozilla-central/source/layout/generic/nsFrame.cpp#441