CSS.... it's Cascading Style Sheets it's a thing used to design threads or websites.... It's not html but it is used in HTML...
http s://en.wikipedia.org/wiki/CSS' (Remove space and ')
Of course not.....
Oh... How unpleasant.....
Yes, because it is a common practice on all forums to have CSS and HTML enabled for normal users
HTML or CSS aren't allowed to be used to design threads or posts on the forum. The option is disabled.