minor css fix

pages/structures/index.vue

@@ -298,12 +298,12 @@
         </div>
       </v-col>
     </v-row>
-    <div class="d-flex w100 justify-center mt-3">
+    <div class="d-flex w100 justify-center">
       <v-btn
         v-if="!parentIsCmf"
         :href="cmfStructuresPageUrl"
         target="_blank"
-        class="my-auto ma-4"
+        class="ma-4"
       >
         <font-awesome-icon :icon="['fas', 'external-link-alt']" class="mr-2" />
         {{ $t('see_national_network') }}