Implement UX feedback on access link sidebar

Why these changes are being introduced:

UXWS has requested some changes to the access link sidebar (and
the full record view more broadly).

Relevant ticket(s):

* [GDT-319](https://mitlibraries.atlassian.net/browse/GDT-319)

How this addresses that need:

* Changes aria-label for the sidebar;
* Updates heading typography to match the filter sidebar heading; and
* Adds top margin to the full record.

Side effects of this change:

None.

app/assets/stylesheets/partials/_record.scss

@@ -1,4 +1,6 @@
 .wrap-full-record {
+  margin-top: 2.4rem;
+
   .record-title {
     font-size: 2.5rem;
     line-height: 1.1;
@@ -48,7 +50,7 @@
 }
 
 .return-to-results {
-  padding: 1.5% 0;
+  padding-top: 2.4rem;
   a {
     padding: 1.5%;
     color: $blue;
@@ -68,5 +70,8 @@
 }
 
 .access-sidebar {
+  @media (max-width: $bp-screen-md) {
+    margin-top: 2.4rem;
+  }
   padding-top: 3%;
 }

app/views/record/_sidebar.html.erb

@@ -1,5 +1,5 @@
 <% if Flipflop.enabled?(:gdt) %>
-  <div role="region" aria-label="Access links and additional information" class="col1q-r sidebar access-sidebar">
+  <div role="region" aria-label="Access and help links" class="col1q-r sidebar access-sidebar">
 <% else %>
   <aside class="col1q-r sidebar">
 <% end %>
@@ -13,7 +13,7 @@
   <% end %>
 
   <% if Flipflop.enabled?(:gdt) && access_type(@record) && gis_access_link(@record) %>
-    <h2 class="title hd-4">Access links</h2>
+    <h2 class="hd-3">Access links</h2>
     <%= render partial: 'access_buttons' %>
   <% end %>