It seems it has a little conflict with discourse-full-width-component and wider logos.
You can quick fix this with 
Paste this in the previously created component after the previous code just to be in one place.
It will shrink the logo.
.desktop-view .d-header .title a {
flex: auto;
}
Update: Hmm I think it probably shrink too much with hidden sidebar… 
I just take a quick look and I think it will be something with grid. But I think better to wait the official way of this because I don’t want to break the header ux with changing on the grid.
@packman please remove this code.