[GeoffR]

Could someone who is familliar with the ePub reader test these patches (one at a time) and let me know how they affect the header/footer size in ePub books when the "Show title" / "Show footer" options are unticked?

Decrease ReaderService viewport height: (libnickel.so.1.0.0.yaml)

Spoiler:

Decrease ReaderService viewport height:
  - Enabled: yes
  - ReplaceBytes: {Offset: 0xB7D00C, FindH: D8 F8 04 30, ReplaceH: 43 46 59 68}
  - ReplaceBytes: {Offset: 0xB7D010, FindH: D8 F8 08 20, ReplaceH: 09 68 9A 68}
  - ReplaceBytes: {Offset: 0xB7D014, FindH: 19 68 12 68, ReplaceH: 12 68 00 3A}
  # Number of pixels to decrease by
  - ReplaceInt: {Offset: 0xB7D016, Find: 0, Replace: 48}

Increase ReaderService viewport height: (libnickel.so.1.0.0.yaml)

Spoiler:

Increase ReaderService viewport height:
  - Enabled: no
  - ReplaceBytes: {Offset: 0xB7D00C, FindH: D8 F8 04 30, ReplaceH: 43 46 59 68}
  - ReplaceBytes: {Offset: 0xB7D010, FindH: D8 F8 08 20, ReplaceH: 09 68 9A 68}
  - ReplaceBytes: {Offset: 0xB7D014, FindH: 19 68 12 68, ReplaceH: 12 68 00 32}
  # Number of pixels to increase by
  - ReplaceInt: {Offset: 0xB7D016, Find: 0, Replace: 48}

I tried them with firmware 4.8.11073 and decreasing the height seemed to work as I would expect, the area available for book content decreased and remained vertically centred, but increasing it didn't work at all. Maybe it will give a clue where to look for a solution though.