Theme issue in firefox

The dark theme is not working correctly

very light gray text on a WHITE background

Firefox 59.02 64 bit on OpenSUSE

I can’t reproduce it here in Firefox 60. Have you tried in a private browser window?

this is the DARK theme !!!
– not very dark

light gray text on white ???
so light that the text is really unreadable

Have you tried the usual things like clearing the cache, delete the cookies, clear site preferences . . .

the cache is auto deleted when firefox shuts down and so are the cookies

firefox is using the QT KDE plasma5 theme and integration

Now in Chromium the dark theme dose work

in “seamonkey-2.49.3.tar.bz2” the dark theme sort of works , some things do and other parts of the site do not
see the screen shot below

it looks like this site is not correctly using my custom “userContent.css” in
" .mozilla/firefox/12345678.default-XXXXXX/chrome/ " folder

the css i NEED for things like text areas NOT to have black text on a black background

i use a dark KDE theme and firefox theme

As said, I cannot reproduce this. Have you tried deactivating your plugins to rule that out (or easier: load the side in a private window)?