set min-width to DropdownMenu of CopyDropdown

src/client/styles/scss/molecules/copy-dropdown.scss

@@ -1,5 +1,7 @@
 .grw-copy-dropdown {
   .dropdown-menu {
+    min-width: 310px;
+
     .dropdown-header {
       margin-bottom: 0.5em;
       font-size: 1.1em;