Apply asterisk (*) with column names using CSS

Hi Creatio Community

I need help in applying red asterisk (*) with the required field values using CSS.

Can you suggest some me method for the same. 

I tried using the below given code in the span tag of the field label in CSS client module of the section but it didn't work.

  .required:after {
    content:" *";
    color: red;
  }

Provide some method of applying the asterisk sign with the required field labels.

Thanks in advance

Sarika