citation-style-language
Tend to UserVoice feedback
There is quite a bit of feedback at http://feedback.mendeley.com/forums/182109-csl-editor. Creating an issue here so we don't forget.
(there are e.g. a large number of reports that the editor doesn't work properly in Chrome: http://feedback.mendeley.com/forums/182109-csl-editor/suggestions/11290860-cannot-use-visual-editor-in-chrome)
There is more feedback at http://support.mendeley.com/customer/en/portal/topics/1002716-csl-editor/questions
I believe the Chrome issue was fixed by the Mendeley team last year and I merged their fix.
I have never seen the 503 with our version of the editor. I suspect it's related to the Mendeley integration, over which we have, obviously no control.
Ah, yes. Looks like their copy is at https://github.com/Mendeley/csl-editor/. I can't find their fork of https://github.com/citation-style-language/csl-editor-demo-site (maybe private?).