MDL-73594 theme_boost: only show lang icon on mobile

theme/boost/scss/moodle/navbar.scss

@@ -123,6 +123,11 @@
                 }
             }
         }
+        @include media-breakpoint-down(sm) {
+            .langbutton {
+                display: none;
+            }
+        }
     }
     .moodle-actionmenu .menubar,
     .action-menu-trigger .dropdown {

theme/boost/style/moodle.css

@@ -20946,6 +20946,9 @@ div.editor_atto_toolbar button .icon {
     content: "\f00c";
     font-size: 0.75rem;
     padding-left: .25rem; }
+  @media (max-width: 767.98px) {
+    .navbar.fixed-top .langmenu .langbutton {
+      display: none; } }
   .navbar.fixed-top .moodle-actionmenu .menubar,
   .navbar.fixed-top .action-menu-trigger .dropdown {
     height: 100%;

theme/classic/style/moodle.css

@@ -20892,6 +20892,9 @@ div.editor_atto_toolbar button .icon {
     content: "\f00c";
     font-size: 0.75rem;
     padding-left: .25rem; }
+  @media (max-width: 767.98px) {
+    .navbar.fixed-top .langmenu .langbutton {
+      display: none; } }
   .navbar.fixed-top .moodle-actionmenu .menubar,
   .navbar.fixed-top .action-menu-trigger .dropdown {
     height: 100%;