It was long-overdue... but #Sengi 1.8.0 is out! π
This version add the much requested THEME SUPPORT functionality! π
And a light theme is already available, check the settings to enable it.
I've also documented the procedure to add a theme if some of you are interested by doing so.
https://github.com/NicolasConstant/sengi/wiki/How-to-Create-New-Theme