ux(modal): tight-form -> gf-form

public/sass/components/_modals.scss

@@ -118,6 +118,8 @@
   }
 
   .share-modal-big-icon {
+    margin-bottom: 2rem;
+
     .fa, .icon-gf {
       font-size: 70px;
     }
@@ -147,3 +149,9 @@
     text-overflow: ellipsis;
   }
 }
+
+.modal-body {
+  .position-center {
+    display: inline-block;
+  }
+}