landing: Add option to show custom navbar message.

static/styles/portico/portico.scss

@@ -1766,3 +1766,22 @@ input.new-organization-button {
 .unsupported_browser_page {
     padding-bottom: 80px;
 }
+
+#navbar-custom-message {
+    font-size: 1rem;
+    background-color: hsl(177, 52%, 55%);
+    background: linear-gradient(145deg, hsl(191, 56%, 55%), hsl(169, 65%, 42%));
+    font-weight: 600;
+    text-align: center;
+    position: relative;
+    top: -40px;
+    margin-left: calc(50% - 50vw);
+    width: 100vw;
+    padding: 10px;
+    border-bottom: 1px solid hsl(177, 52%, 55%);
+
+    a {
+        color: hsl(0, 0%, 100%);
+        text-decoration: underline;
+    }
+}

templates/zerver/landing_nav.html

@@ -1,5 +1,10 @@
 {% if not isolated_page %}
 <nav class="portico-header">
+    {% if landing_page_navbar_message %}
+    <div id="navbar-custom-message">
+        {{ landing_page_navbar_message |safe }}
+    </div>
+    {% endif %}
     <div class="content">
         <a class="brand logo" href="{{ root_domain_uri }}">
             <svg class="brand-logo" xmlns="http://www.w3.org/2000/svg" width="100%" height="100%" viewBox="0 0 40 40" version="1.1">

zerver/context_processors.py

@@ -134,6 +134,7 @@ def zulip_default_context(request: HttpRequest) -> Dict[str, Any]:
         'settings_comments_path': settings_comments_path,
         'platform': platform,
         'allow_search_engine_indexing': allow_search_engine_indexing,
+        'landing_page_navbar_message': settings.LANDING_PAGE_NAVBAR_MESSAGE,
     }
 
     context['OPEN_GRAPH_URL'] = '%s%s' % (realm_uri, request.path)

zproject/default_settings.py

@@ -365,6 +365,10 @@ BILLING_ENABLED = False
 
 FREE_TRIAL_DAYS = None
 
+# Custom message (supports HTML) to be shown in the navbar of landing pages. Used mainly for
+# making announcements.
+LANDING_PAGE_NAVBAR_MESSAGE: Optional[str] = None
+
 # Automatically catch-up soft deactivated users when running the
 # `soft-deactivate-users` cron. Turn this off if the server has 10Ks of
 # users, and you would like to save some disk space. Soft-deactivated

zproject/dev_settings.py

@@ -156,6 +156,7 @@ SEARCH_PILLS_ENABLED = bool(os.getenv('SEARCH_PILLS_ENABLED', False))
 
 BILLING_ENABLED = True
 FREE_TRIAL_DAYS = None
+LANDING_PAGE_NAVBAR_MESSAGE = None
 
 # Test Custom TOS template rendering
 TERMS_OF_SERVICE = 'corporate/terms.md'