I used the Tweak/explode feature to edit the text only of an azw3 ebook, fixing some hyphenation and running spell check on the .html text files. I did not edit any of the html or css code. I used the OS X 10.8.3 TextEdit program to make the changes. After I rebuilt the ebook and put it on my Kindle Touch, the font was tiny. To resurrect the desired font size, I reconverted the modified ebook.
Shouldn't the font be unchanged if the only tweaking is to the text?