Support Problem with Font Awesome icon

[sudo_pseudo]

Hi guys I have added affect in the username and it is working fine but the problem is with the icon (before username)
I am using Font Awesome icon and it is not getting loaded, instead of it a rectangle box is showing there. Can anyone tell me how to solve it or the correct method to add icon before username.

 

[d3va]

if u have the 2.3 version it would be differenet way to code it

 

[sudo_pseudo]

if u have the 2.3 version it would be differenet way to code it

Yes I am using v2.3 can you tell me how to code it

 

[d3va]

Yes I am using v2.3 can you tell me how to code it

.username--style3:before {
    .m-faContent(@fa-var-flower-tulip); /* Replace with appropriate Font Awesome variable */
    color: inherit;
    padding-right: 5px;
    display: inline-block;
}