Fix mediatag width in polls

www/form/app-form.less

@@ -265,6 +265,11 @@
                         input:invalid {
                             border: 1px solid @cp_form-invalid;
                         }
+                        media-tag {
+                            & > * {
+                                max-width: 100%;
+                            }
+                        }
                     }
                     .cp-form-input-block {
                         //width: @form_input-width;