OT: techno help w/ fonts?

WHY do all my posts have regular size text fonts then small size fonts then back to regular size fonts.... can be 1 word in a sentence, or a whole sentence or two....Im so sick of constantly editing my posts to get em to look right.  Its drivin me craaaazzzzyyy!  Its only here on OH...no where's else

Heeelp please

I noticed your posts with the different sized fonts too but I thought that was done intentionally.  I wish I could help but I have no idea.