[jhowell]

I can't tell you why Amazon's Look Inside gives different results across your books. I know that other author/publishers have complained about odd behavior in that feature.

One issue is that your book will be delivered to most customers using newer Kindle apps and devices in KFX format. Conversion to KFX applies several heuristics meant to improve the layout of text within a book, but this doesn't work well with what you are doing by using a grid of individual piece images to make a chess board. While your second image with no gaps may be what you prefer, the actual books your readers see will look more like the first image in many cases.

I had the free sample of your book "Think Like a Computer" delivered to Kindle for PC on my computer. It was delivered in KFX format. I have attached some screenshots of how the first chess board in that book appears with various font size and line spacing settings.

I believe that you would have better results if you made the entire chess board a single image instead.