The texture for tabs on the recipe book is slightly misaligned. To reproduce:
1. Open the recipe book, preferably against a bright background like snow or quartz
2. Select the 2nd tab from the top
3. Observe the grey line of pixels above the black diving line of pixels between the 2nd and 3rd tab become 2px in height instead of 1px like it was before. It should stay 1px, just like creative mode inventory tabs that don't change width when selected.
4. Look at the first, fourth or fifth tab: it's missing the black outline on the top
5. Look at the bottom of the first tab: it's got a double black outline