Comment font larger after enabling csslab feature flag

I enabled Feature.enable(:csslab) on a local CE instance. The font for comments now appear larger that it did before. With the feature disabled, Feature.disable(:csslab), the font is normal size again.

Disabled csslab Enabled csslab
Screen_Shot_2018-12-10_at_10.28.18_AM Screen_Shot_2018-12-10_at_10.27.21_AM

Happens on both Chrome and Safari.

Edited by Clement Ho