Add dark theme support

[luclu7]

The old automatic "dark" theme was not awesome, so I tried adding a better support. I'm not a Sass expert, Old:

New: 

[dhenry123]

Thank you very much for your interest. Could you set the logo background to the same colour as the header background?

.header .logo {
  margin: 4px;
  cursor: pointer;
  background-color: inherit;
  padding: 6px 6px 0 0;
  opacity: .7;
}

[luclu7]

The colors of the logo are a bit too dark to contrast correctly in my opinion

Inverse is waaaaay too awkward

This is filter: brightness(0) invert(1);, it's a bit sad without any color

Or maybe, just a "proper" rounded white background?

Which one would you prefer?

[dhenry123]

I've created a new branch: "logodarkmode". Could you pull it and add the new file "client/public/assets/MytinyDC_logo-brand-full-darkmode.png" to your branch, then define the darkmode css accordingly... Thank you so much

[luclu7]

This logo looks great !

[luclu7]

By the way, beware, the tag of the last release is 1.20 instead of 1.2.0

[dhenry123]

Thanks, I'll now avoid publishing a release while having breakfast. :)