Actually the code should be like below. (.username included in h2)
.names span.username a::before {content: "@"}
.names span h2.username::before {content: "@"}
.user-main .about .details h2.username::before {content: "@"}
@tophee Also I guess in your website you prioritized the username. That’s the problem. Then the code should be like below (not yet verified)
.names span.username a::before {content: "@"}
.names span h1.username a::before {content: "@"}
.user-main .about .details h1.username a::before {content: "@"}