I just tried this out with the 4.0.0.beta.2 version and I have two comments:
- The red border I find too harsh, I would suggest using 1px instead of 2px
- The white of the "Node-RED" is also a bit harsh with the black background, it also jumps into my eyes. Perhaps a little less white?
- The glare affect of the red border is also enhanced when the sidebar is greyed out (e.g. when opening the settings):
The border effect is different than the screenshot above since that screenshot is expanded and hence the red border is thicker, so hard to get a feeling from that.
Just my 2cents
Edit: added 3rd point
Edit2: of course this is very depended on my screen and it's configuration, so I might well be well off the mark...