[DiapDealer]

But Book View should be rendering the same as Preview in that regard. My BV and Preview render identically. I'm just not following why anyone would have to increase BV's font size to make Preview readable. They should match. They're the same thing, afterall (minus editablility, of course).

Never mind ... I see what you're (the OP) doing now. You've got different zoom levels set in Preview than you do in Book View. Don't change the base font sizes (through css, or through display settings) just to make Preview "legible." Just reset the zoom level on both widgets so they match (View-->Zoom Reset or Ctrl+0). Then if you Zoom in or out on one (BV), You need to do the same on the other (Preview). But only if you need to. I recommend leaving the zoom-level at default for both Widgets and changing the fontsize in Preferences-->Appearance if you require a larger/smaller font. As you can see, "zooming" can get you all messed up (especially when you accidentally do it with a button press and/or a mouse-scroll).