put size specification in btn-lg

src/client/styles/scss/_user.scss

@@ -89,9 +89,9 @@ $easeInOutCubic: cubic-bezier(0.65, 0, 0.35, 1);
   }
 
   .btn.btn-bookmark {
-    width: 50px;
-    height: 50px;
     &.btn-lg {
+      width: 50px;
+      height: 50px;
       font-size: 1.5em;
     }
   }