Add card styles

app/frontend/styles/_card.scss

@@ -0,0 +1,7 @@
+.app-card {
+  @include govuk-responsive-padding(4);
+  @include govuk-font($size: 19);
+  background-color: govuk-colour("light-grey");
+  display: block;
+  position: relative;
+}

app/frontend/styles/application.scss

@@ -14,6 +14,7 @@ $govuk-global-styles: true;
 
 @import "accessible-autocomplete";
 @import "button";
+@import "card";
 @import "document-list";
 @import "figure";
 @import "filter";