Fix footer on smaller screens

app/assets/stylesheets/govuk-frontend/overrides.scss

@@ -28,3 +28,31 @@
     padding-bottom: 90px;
   }
 }
+
+.govuk-footer__navigation {
+  -webkit-flex-wrap: wrap;
+  -ms-flex-wrap: wrap;
+  flex-wrap: wrap
+}
+
+.govuk-footer__section {
+  -webkit-flex-basis: 200px;
+  -ms-flex-preferred-size: 200px;
+  flex-basis: 100%;
+}
+
+@include govuk-media-query($from: tablet) {
+
+  .govuk-footer__navigation {
+    -webkit-flex-wrap: nowrap;
+    -ms-flex-wrap: nowrap;
+    flex-wrap: nowrap
+  }
+
+  .govuk-footer__section {
+    -webkit-flex-basis: 200px;
+    -ms-flex-preferred-size: 200px;
+    flex-basis: 200px;
+  }
+
+}