Top bar not displaying on mobile devices

Hey there,

my top bar which only consist of the social media buttons does not display on mobiles and tablets (or only displays as a fine line)

I have added this CSS code that I have been given:

@media handheld, only screen and (max-width: 900px) {
#header-bar { display: block !important; }
}

But it didnt change it.

Anything else I could try?