Custom CSS red text

On the Custom CSS many codes are in red text.
Is it a trouble?

Hi there

No, it’s not, they are CSS selector and that’s how WordPress highlights them

Actually there was a problem.
I post it for other users.
I forgot to put a curly bracket so the code below didn’t work


Ok, sorry, I just spotted, you don’t have closing curly braces here: Screenshot by Lightshot on the second line