Redesign local nav for GDT

Why these changes are being introduced:

The Geodata app requires links to GIS resources at MIT in the local
nav. It also no longer requires the app name in the local nav, as
GDT-125 moved this to the main header.

Relevant ticket(s):

* https://mitlibraries.atlassian.net/browse/GDT-125
* https://mitlibraries.atlassian.net/browse/GDT-124

How this addresses that need:

This restyles the local nav as specified, provided the GDT feature
is enabled. It also makes the title in the nav conditional on whether
the `PLATFORM_NAME` environment variable is present. (This toggles the
name in the header.)

Side effects of this change:

None.

Author: jazairi

app/assets/stylesheets/application.css.scss

@@ -8,6 +8,7 @@
 @import "partials/_alerts";
 @import "partials/_filters";
 @import "partials/_global_alerts";
+@import "partials/_local_nav";
 @import "partials/_pagination";
 @import "partials/_panels";
 @import "partials/_search";

app/assets/stylesheets/partials/_local_nav.scss

@@ -0,0 +1,42 @@
+.wrap-outer-header-local {
+  .local-identity {
+    padding: 1rem 0;
+  }
+
+  .wrap-header-local {
+    padding-top: 1rem;
+    padding-bottom: 1rem;
+
+    .wrap-local-nav {
+      margin: 0;
+
+      .local-nav {
+        display: flex;
+        font-weight: $fw-bold;
+
+        .wrap-gis-links {
+          text-align: right;
+          margin-left: auto;
+
+          :first-child:after {
+            margin: 0 5px;
+          }
+
+          .nav-item {
+            padding-left: 5px;
+            padding-right: 5px;
+            margin: 0;
+            text-decoration: underline;
+            &:hover,
+            &:active,
+            &:focus {
+              transition: all .25s ease-in-out 0s;
+              color: $brand-primary-accent;
+              background-color: #fff;
+            }
+          }
+        }
+      }
+    }
+  }
+}

app/views/layouts/_site_nav.html.erb

@@ -1,14 +1,21 @@
 <div class="wrap-outer-header-local layout-band">
   <div class="wrap-header-local">
-    <div class="local-identity">
-      <h2 class="title title-site"><a href="/">TIMDEX UI</a></h2>
-    </div>
-    <div class="wrap-local-nav">
-      <div class="wrap-bar">
-        <nav class="local-nav" aria-label="Main menu">
-          <%= nav_link_to("Home", root_path) %>
-        </nav>
+    <% unless ENV['PLATFORM_NAME'] %>
+      <div class="local-identity">
+        <h2 class="title title-site"><a href="/">TIMDEX UI</a></h2>
       </div>
+    <% end %>
+    <div class="wrap-local-nav">
+      <nav class="local-nav" aria-label="Main menu">
+        <%= nav_link_to("Home", root_path) %>
+        <% if Flipflop.enabled?(:gdt) %>
+          <div class="wrap-gis-links">
+            <%= nav_link_to("GIS at MIT", "https://libraries.mit.edu/gis") %>
+            <span class="nav-divider" aria-hidden="true">|</span>
+            <%= nav_link_to("Ask GIS", "https://libraries.mit.edu/ask-gis") %>
+          </div>
+        <% end %>
+      </nav>
     </div>
   </div>
 </div>