[GeoffR]

I've updated the attachment in post #1 to add the `ePub fixed/adjustable top/bottom margins` patch. Here it is if you want to copy and paste rather than download the attachment again:

`ePub fixed/adjustable top/bottom margins` (4.6.9660, libnickel.so.1.0.0.patch)

Spoiler:

<Patch>
patch_name = `ePub fixed/adjustable top/bottom margins`
patch_enable = `no`
# patch_group = `ePub padding-bottom alternatives`
#
## This patch sets the @page margin sizes in epubs, overriding any @page margin
## set in the book's CSS stylesheet (but not in the XPGT stylesheet, see below).
##
## By default the top and bottom margins are set to be adjustable, their size
## similar to the left/right margin size set by the adjustment slider. There
## are options to set the top and/or bottom margin to a fixed size instead.
##
## Note that @page margins are seperate from (and overlap) both the body margins
## set in the book and the left/right margins set from the adjustment slider,
## and are added to any page margins set in the Adobe XPGT stylesheet if the
## book has one (e.g. page-template.xpgt). For this reason you might want to
## consider using the Modify ePub Calibre plugin to remove any body margins and
## XPGT stylesheet margins before sideloading the book, or perhaps enabling the
## `Ignore ePub Adobe XPGT stylesheet (page-template.xpgt)` patch.
##
## Also note that a side-effect of this patch is that the body padding-bottom is
## removed from the built-in stylesheet, which means that there will no longer
## be a blank line added automatically at the end of chapters.
##
## See at the bottom of the patch for replacement values that can be used to
## tune the size of the margins to suit different devices and reading modes.
#
#
# Push an extra 8 bytes of scratch space onto the stack
replace_bytes = 4EA71C, C1 B0, C3 B0
replace_bytes = 4EA71E, 02 AF, 04 AF
# Save this value for the third stack argument of the following function call
replace_bytes = 4EAAB2, AD F8 04 20, 02 92 01 92
# getReadingLineHeight(...) --> getReadingLeftMargin(...)
replace_bytes = 4EAB04, AD F7 D6 EA, 8D F7 48 EE
# (Setup call to QString.arg)
replace_bytes = 4EAB08, 20 22 4F F0 FF 33, 00 23 01 22 0A 21
replace_bytes = 4EAB0E, 07 F1 58 09, 00 93 01 91
replace_bytes = 4EAB12, AD F8 04 20 00 93, 42 43 92 08 01 3A
replace_bytes = 4EAB18, 48 46 67 23, B8 BF 00 22
replace_bytes = 4EAB1C, 00 22 29 46, 1A A8 29 46
# QString.arg(double, ...) --> QString.arg(int64, ...)
replace_bytes = 4EAB20, 99 F7 E8 EA, 8D F7 8E E9
#
# (There wasn't room to load r9 above)
# mov r1,r9; --> adds r1,sp,#104
replace_bytes = 4EAB24, 49 46, 1A A9
# (Remember to pop scratch space if necessary)
#
#      padding-bottom: %1em !important;\n
# --> }@page{margin:%1px 00px %1px}body{
find_base_address = `\x20\0p\0a\0d\0d\0i\0n\0g\0-\0b\0o\0t\0t\0o\0m\0:\0 \0%\01\0e\0m\0 \0!\0i\0m\0p\0o\0r\0t\0a\0n\0t\0;\0\n\0`
replace_string = 0000, `\x20\0p\0a\0d\0d\0i\0n\0g\0-\0b\0o\0t\0t\0o\0m\0:\0 \0%\01\0e\0m\0 \0!\0i\0m\0p\0o\0r\0t\0a\0n\0t\0;\0\n\0`, `}\0@\0p\0a\0g\0e\0{\0m\0a\0r\0g\0i\0n\0:\0%\01\0p\0x\0 \00\00\0p\0x\0 \0%\01\0p\0x\0}\0b\0o\0d\0y\0{\0`
#
#
# *** Replacement values start here, don't change anything above ***
#
# Optional replacement value: Uncomment for a FIXED TOP MARGIN size in px,
# default 25px. Replacement value is margin size, two digits separated by \0
# (Leave commented out for an adjustable top margin.)
#replace_string = 001C, `%\01`, `2\05`
#
# Optional replacement value: Uncomment for a FIXED BOTTOM MARGIN size in px,
# default 00px. Replacement value is margin size, two digits separated by \0
# (Leave commented out for an adjustable bottom margin.)
#replace_string = 0030, `%\01`, `0\00`
#
# Optional replacement value: Uncomment to set the minimum LEFT/RIGHT MARGIN
# size in px, default 15px. (This margin will overlap the left/right margin
# set with the adjustment slider, not add to it.) Replacement value is margin
# size, two digits separated by \0
#replace_string = 0026, `0\00`, `1\05`
#
base_address = 000000
# Replacement value: Sets the step-size of the ADJUSTABLE top/bottom margin
# (if any) in quarter-pixels. These suggested values should be very close to
# the 1% step size of the left/right margins set by the slider. Larger values
# will make the top/bottom margins larger than the left/right margins.
# Suggested values:
#   24 (Touch/Mini), 30 (Glo/Aura/Aura2ed), 43 (AuraHD/H2O/GloHD), 56 (Aura One)
replace_int = 4EAB0A, 1, 30
#
# Replacement value: Set this to the size of the device's built-in top margin,
# in pixels. This value is subtracted from the adjustable top/bottom margin
# (if any) to compensate for any unremovable built-in top margin.
# Suggested values are:
#   0 For full-screen reading mode (fullScreenReading=true, all devices)
#  15 for normal reading mode (with custom or disabled footer, all devices)
replace_int = 4EAB16, 1, 0
</Patch>

The `Custom page refresh options` patch is not going to work with this firmware, will have to start from scratch with that one.