Code page doesn't support line numbers over 999
This doesn't happen with me, it's correctly showing the amount of code lines
Maybe it depends from browser (I use Waterfox Classic).
No problem with Waterfox Classic for me too for JS script.
Just it seems not have line number for UserCSS code.
By example:
Flickr WideScreen - BigONE
Have you a test link?
https://greasyfork.org/en/scripts/407284-imdb-scout-mod/code
Same on Pale Moon too.
I understand the (no)problem now:
The line number work perfectly, but the start of 1000 it's just hidden:
so, you see just "000".
In fact, if you watch better:
".000"
2 Screenshots with your example at line 999/1000:
1 - without CSS tweak: line number truncated.
2 - with a CSS tweak which reveal the whole line number...
Code page doesn't support line numbers over 999, numbering "restarts" from 000.
Diff versions in History could show line numbers too.