Well, right after I posted that, it went away. But it was there yesterday, and the phone was off overnight charging, and it was there this morning. Then by some hocus-pocus iPhone magic...it was gone!!
I think that I accidentally pressed shift and the F12 button at the same time while I was trying to type something else on Facebook. Now the screen is like enlarged and the text all looks like it's a bigger font. But the only thing that has changed is Facebook. All of the other websites on my internet browser look the same. Do you know how I can change it back? Thanks!