I was testing my new site in multiple browsers and when I started testing it on Firefox, there was a page that was all screwed up. I kept looking and looking at my CSS but nothing was wrong. THEN I finally found it:
I put: padding-bottom: 62.3%%, with TWO percentage signs. Apparently this is okay in Chrome and it didn't screw up my layout. But this also got me very confused because it worked in Chrome but not in Firefox.
NOTE-TO-SELF: TEST ON OTHER BROWSERS BECAUSE CHROME IS TOO FORGIVING.