Broken with latest Slack 3.0.0 update (macOS)
Doesn't work for me either.
I would really appreciate it this get's fixed. Thanks!
I found a fix for Ubuntu. instead of changing the /usr/lib/slack/app.asar.unpacked/src/static/index.js i changed this file /usr/lib/slack/app.asar.unpacked/src/static/ssb-interop.js, where i put the same code from the Readme of the repo and it worked perfectly.
Found the solution by looking at a similar repo that had a similar issue, found the solution by reading the comment: https://github.com/laCour/slack-night-mode/issues/73#issuecomment-287467332
bogdanRada solution worked for me in macOS Sierra, thank you!
bogdanRada solution worked for me in macOS High Sierra, thanks! @jcredmond ^^
@bogdanRada Thanks! Worked on macOS High Sierra - Slack 3.0.0.
Worked for me as well! For clarity, the path on MacOS is now:
/Applications/Slack.app/Contents/Resources/app.asar.unpacked/src/static/ssb-interop.js
Worked for me too, thank you bogdanRada! macOS Sierra - Slack 3.0.0
After killing all the processes on Ubuntu 16.04 this worked for me too
bogdanRada's solution works on Windows 10 as well. Thanks!
For clarity, the Windows path to the file is: C:\Users\{username}\AppData\Local\slack\app-3.0.0\resources\app.asar.unpacked\src\static
That location definitely modified the visual effects, but themes no longer match up. Do those need to be updated as well?
Not working on Linux currently.
But it's working with https://github.com/laCour/slack-night-mode/issues/73#issuecomment-287467332
Note: you need to modify both index.js and ssb-interop.js to get the full functionality (both sidebar and main content window) as before.
Thanks @bogdanRada.
Also working on windows 10!
EDIT: I just found a little "issue"

The solution from @bogdanRada worked great on Windows 10 with Slack 3.0.0! Thanks
Seems like Slack updated smth internally, and after that messages' text color was always dark grey for me. Fixed it with:
.c-message__body{
color: #ffffff;
}
@yuyoyuppe where is this added?
@hainesnr append it to rules in the let customCustomCSS
@yuyoyuppe Thanks for posting that. Do you know how we could change the font color for the names on each post as well?
@Cannellizer Not sure what you mean, though you could try inspecting html yourself by adding smth like this to the cssPromise callback:
setTimeout(function(){
var fs = require('fs');
fs.appendFileSync("C:/slack.html", document.head.innerHTML + document.body.innerHTML);
}, 10000);
It was a quick fix though, maybe there's a better way how to get html/style those of which I'm not aware. I think maintainers'll introduce a proper fix soon :)
Names are still dark-grey after the patch :(