fix header on desktop (#31)

src/courseware/course/CourseHeader.jsx

@@ -50,7 +50,7 @@ export default function CourseHeader({
         <Dropdown className="user-dropdown">
           <Dropdown.Button>
             <FontAwesomeIcon icon={faUserCircle} className="d-md-none" size="lg" />
-            <span className="d-none d-mb-block">
+            <span className="d-none d-md-inline">
               {authenticatedUser.username}
             </span>
           </Dropdown.Button>

src/index.scss

@@ -66,7 +66,9 @@ $primary: #1176B2;
   .user-dropdown {
     .btn {
       height: 3rem;
-      padding: 0 .5rem;
+      @media (min-width: map-get($grid-breakpoints, 'sm')) {
+        padding: 0 .5rem;
+      }
     }
   }
 }