Here is a patch to expose all Gargoyle menus.
You have to compile these changes and either copy the gargoyle_header_footer binary to your router or build a firmware that you flash onto your router.
It is not a theme. If you should choose to make a theme around the new structure of the menus, it will (most likely) not be compatible with the vanilla gargoyle_header_footer - so don't submit it for inclusion, because it won't look as you intend.
The patch file is compatible with the existing themes - all it does is shoe the extra menu options.
Seek the answers to your CSS questions elsewhere.
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1. Download & extract the patch here
2. To the gargoyle source you obtained from github, here, or from your own hard drive, apply the patch. The patch is sensitive *relative* to the gargoyle source.
cd /path/to/gargoyle_folder
patch -p0 -i gargoyle_header_footer.patch
3. compile
3a. if you already have a working buildroot environment:
cd /path/to/gargoyle_folder/ar71xx_src (or your platform)
make package/gargoyle/compile
[make a backup of your existing gargoyle_header_footer by openening a separate ssh seession & cp /usr/bin/gargoyle_header_footer /usr/bin/GHF-backup]
scp /path/to/gargoyle_folder/gargoyle/ar71xx-src/build_dir/target-mips_r2_uClibc-0.9.33.2/gargoyle/ipkg-ar71xx/gargoyle/usr/bin/gargoyle_header_footer root@192.168.1.1:/usr/bin
One other note: if you build a theme around this & you use it to hide & show menus on hover, don't expect it work well on touch devices. There are a few onClick=return true that deal with ios issues, but don't expect perfection on touch devices. hover is a challenge on touch devices.