can you show us the headers? the css/js files?

LouisGac wrote: can you show us the headers? the css/js files?

Is this what you mean? (please see attached)

please, turn debug mode on, so the asset manager is not used.

LouisGac wrote: please, turn debug mode on, so the asset manager is not used.

And then what should I do afterwards?

I've turned it on and rerun the survey.

then reload the survey in a private windows.

LouisGac wrote: then reload the survey in a private windows.

By private you mean like Incognito in Chrome? Because it gives me an error when I try to open incognito the preview.

yes, I mean Incognito mode.
you can publish your survey or allow public access to the preview.

Is it possible to find out the issue without publishing?
The survey is corporate and cannot be made available to the public.

yes: the problem is that you're changin the CSS without refreshing the cache.
Please: develop your theme with debug mode on, refresh your browser cache at each change, and read

Maybe there is a problem with the autorefresh of the theme editor, I'll have a look

For some reason, when I extend a theme again, then the CSS code works. But for the previously extended one it doesn't...
And the strange thing is that I had the theme set with that CSS code, and from today it just went back to default and wasn't responding to changes anymore. So I had to extend the theme again. BUT.. who knows, maybe it will happen again - one week after, the theme will stop loading custom.css and I have a big issue in my organization. I would like to avoid such surprises.

it's the asset manager + the browser cache.
turn debug mode on: no more asset manager (the real file you're editing is loaded), but then browser cache problem (the browser uses its local version)

Solution: turn debug mode on, refresh your browser cache.

but normally, the theme editor should refresh the assets at each save. I'll check what's going on