Version 63.0b3 right now, first noticed this in the update that introduced ‘Left-align Viewport’ in responsive mode.
After a while of working in a tab with the inspector open it will stop loading CSS in. Seems to happen pretty consistently, I’ve been disabling add-ons until I’ve just had RES and Vue Tools open now and it’s still persistent.
Opening a new tab will return things to normal, refreshing doesn’t.
Yes - this is what I’m working on now, but it happens with every page I load in Firefox. This started happening like a week ago, and I didn’t pay any attention at first but now it’s not usable for me.
Thanks for adding the gif @abv ! I see you are using Responsive Design Mode, and indeed it seems that “Inspect Element” is broken when Responsive Design Mode is enabled.
I just checked Beta and Dev Edition, and can’t reproduce the issue (with or without RDM).
Can you share more details about your setup? Do you have steps to reproduce the issue?