When the server runs for a while the GitHub css might change and thus the paths are invalid because you keep them cached forever.
A restart always helps.
The solution could be to grab the GitHub CSS url on every request or do that periodically every 10s
That's by design. I did not expect anyone to run GFMS longer than 1 day, which is about as long as it takes for the Akamai hosted CSS files to become invalid, on rough average.
But yeah this bothers me too as I ended up having GFMS running on my machine continuously, and have to restart it from time to time.
I will fix this in the coming days.
sweet! btw, I have this running on one of our servers 24/7 and it works great so for, this issue aside