[gnome-builder/wip/gtk4-port] libide/greeter: use flat for greeter headerbar

[Christian Hergert <chergert src gnome org>]

commit 982258ab26fa77f9fb9d8e4e2873ea783ffef965
Author: Christian Hergert <chergert redhat com>
Date:   Wed Apr 6 18:13:44 2022 -0700

    libide/greeter: use flat for greeter headerbar
    
    The greeter will likely go through a bunch more changes, but we want to
    make it look less like the rest of the application and more of a landing
    page which is temporary. A flat style might be one way to do that.
    
    Longer term, I'd also like to rethink the flow between greeter pages
    since they need so much surgery anyway.

 src/libide/greeter/ide-greeter-workspace.ui | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/src/libide/greeter/ide-greeter-workspace.ui b/src/libide/greeter/ide-greeter-workspace.ui
index 52417fb46..86dab0ca3 100644
--- a/src/libide/greeter/ide-greeter-workspace.ui
+++ b/src/libide/greeter/ide-greeter-workspace.ui
@@ -5,6 +5,13 @@
     <child type="titlebar">
       <object class="IdeHeaderBar" id="header_bar">
         <property name="menu-id">ide-greeter-workspace-menu</property>
+        <child internal-child="headerbar">
+          <object class="AdwHeaderBar">
+            <style>
+              <class name="flat"/>
+            </style>
+          </object>
+        </child>
         <child type="title">
           <object class="AdwWindowTitle" id="title"/>
         </child>