This is actually a theme-specific revision, not a core change. I'd suggest opening an issue at https://github.com/nodebb/nodebb-theme-persona/issues and detailing the necessary changes there. Thanks.
CSS Chats problem With Black Themes
I have problem with Chats CSS with Black themes,
I don't see the text on Chats windows :
On mouse Over
Can you help me with that ?
@downpw If you know how to use css, just change the text in the chat to white.
but add another class to make it the regular color while hovering, you may need to use !important
Resolved for me