“Custom class” means text you added in “Extra class name” field https://prnt.sc/jg65ju, like – http://prntscr.com/jg7139
in this case, the custom css should be:
.top-bar p:empty {
display:none;
}
.top-bar .widget_icl_lang_sel_widget, .top-bar .top-content {
display: inline-block;
}
.top-bar .top-content {
margin-top: 10px;
position: absolute;
left: 50%;
transform: translateX(-50%);
}
Regards