Thank you very much guys. So cool!
That's exactly what I desired after status4ever became disabled in Firefox Quantum.

It doesn't work with private site, like intranets.

Edit: It worked, thanks! Also, could you make an option to change the position to bottom?

Please add option to be inside the address bar.

Was going to write "please add options to change size and color" but it's already there =)
Great small extension

Really awesome! Does what it's suppose to and is very inconspicuous and discreet!

i loved it

in addition, it lets you adjust color and width of the loading bar.
adds back a teensy bit of customizabilty to FF57+ ...

might look a bit irritating on websites (some ajax-y rich web apps) that bring their own loading or scroll progess indicator. didn't check that yet and will see how it works out.