What does the $ sign mean in css and how validate it?

Question

in one of my css code I saw this code:

 .\37 u, .\37 u\24 {
            width: 58.3333333333%;
            clear: none;
            margin-left: 0;
        }

I try convert it ...

.7u, .7u$ {
            width: 58.3333333333%;
            clear: none;
            margin-left: 0;
        }

Now I try validate it...so I add 'i' before number....but what is '$' sign? if it is important how can I validate as a normal code?

.i7u, .i7u$ {
            width: 58.3333333333%;
            clear: none;
            margin-left: 0;
        }

I think It is just a symble but I afraid I am wrong

Answer 1

It's just an invalid character to use in a class name, nothing more. CSS3 allows for UTF-8 bases characters in class names, with some exceptions:

~ ! @ $ % ^ & * ( ) + = , . / ' ; : " ? > < [ ] \ { } | ` #

Which characters are valid in CSS class names/selectors?