enhance(ui): restore to show code block lang when narrow screen

src/main/frontend/extensions/code.css

@@ -18,7 +18,6 @@
     right: 0;
     /* margin-top: 4px; */
     z-index: 9999;
-    display: none;
     padding: 4px 6px;
     line-height: 1em;
     opacity: .8;
@@ -42,12 +41,6 @@
       font-family: Fira Code, Monaco, Menlo, Consolas, 'COURIER NEW', monospace;
     }
   }
-
-  @screen md {
-    &-lang {
-      display: flex;
-    }
-  }
 }
 
 .CodeMirror {