[gnome-boxes/wip/exalm/light: 1/5] welcome-tutorial: Fix header bar in light variant

[Alexander Mikhaylenko <alexm src gnome org>]

commit fdfea8fdcaa5416f17010ea4670d63157c80c85b
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Sat Dec 25 19:28:57 2021 +0500

    welcome-tutorial: Fix header bar in light variant

 data/ui/welcome-tutorial.ui | 8 ++++----
 src/welcome-tutorial.vala   | 6 ++++--
 2 files changed, 8 insertions(+), 6 deletions(-)
---
diff --git a/data/ui/welcome-tutorial.ui b/data/ui/welcome-tutorial.ui
index ba838445..f9acb298 100644
--- a/data/ui/welcome-tutorial.ui
+++ b/data/ui/welcome-tutorial.ui
@@ -8,14 +8,14 @@
     <property name="height-request">600</property>
     <property name="width-request">710</property>
     <signal name="delete-event" handler="gtk_widget_hide_on_delete"/>
-    <style>
-      <class name="welcome-tutorial"/>
-    </style>
 
     <child internal-child="vbox">
-      <object class="GtkBox">
+      <object class="GtkBox" id="inner_box">
         <property name="visible">True</property>
         <property name="border-width">0</property>
+        <style>
+          <class name="welcome-tutorial"/>
+        </style>
 
         <child>
           <object class="GtkBox" id="indicator-spacer">
diff --git a/src/welcome-tutorial.vala b/src/welcome-tutorial.vala
index 88b853b6..24c7f3e6 100644
--- a/src/welcome-tutorial.vala
+++ b/src/welcome-tutorial.vala
@@ -4,6 +4,8 @@
 
 [GtkTemplate (ui = "/org/gnome/Boxes/ui/welcome-tutorial.ui")]
 private class Boxes.WelcomeTutorial : Gtk.Dialog {
+    [GtkChild]
+    private unowned Box inner_box;
     [GtkChild]
     private unowned Carousel paginator;
     [GtkChild]
@@ -24,8 +26,8 @@
         }
 
         provider = new CssProvider ();
-        get_style_context ().add_provider (provider,
-                                           STYLE_PROVIDER_PRIORITY_APPLICATION);
+        inner_box.get_style_context ().add_provider (provider,
+                                                     STYLE_PROVIDER_PRIORITY_APPLICATION);
 
         on_position_changed ();
     }