Persian Menu

Try adding this to your custom/child-theme css:

header .navbar .nav>li>a:first-letter{font-size: inherit;}

Any chance to see your site?
p.s.
neither adding !important?
inherit !important;

Ah maybe I got:

.nav-collapse .nav li a {
    display: inline;
}
@media (max-width: 979px){
    .navbar .navbar-inner .nav li {
        margin-top: .8em;
        margin-bottom: .8em;
    }
}

Is this acceptable for you?

Glad you solved 🙂