If you're on the iPad or whatever you have, copy the two JavaScript codes from method B to the notes app. Remember which is which. Then create two bookmarks, I'm hoping you know how to do that, after you are done doing that, go back and edit those two new bookmarks you just created. Name one font- and the other font+ or whatever you like. Go back to your notes and copy the font- code first, go to your newly named font- bookmark, delete the URL which is the second item when you edit the bookmark. After deleting the URL, paste the font- in there and you've created the font- bookmark. Now do the same to the font+ with the font+ code and bookmark.
If you want to have the font size tabs stay permanently on the tabs, go to settings, safari, and turn on "always show bookmarks bar". Move the two font size bookmarks to the bookmark bar folder of the bookmarks tab. Now the font sizes are on the tab.
Good luck.