[libshumate] simple-map: Use .osd style class

[Corentin Noël <corentinnoel src gnome org>]

commit 9594637cdf10f0013fccacd79147b966981d2c87
Author: James Westman <james jwestman net>
Date:   Wed Apr 13 14:25:04 2022 -0500

    simple-map: Use .osd style class
    
    Use the .osd style class for the zoom in/out buttons in
    ShumateSimpleMap.

 data/shumate-simple-map.ui | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/data/shumate-simple-map.ui b/data/shumate-simple-map.ui
index d11764e..07ec0c2 100644
--- a/data/shumate-simple-map.ui
+++ b/data/shumate-simple-map.ui
@@ -38,6 +38,9 @@
               <object class="GtkButton">
                 <property name="tooltip-text">Zoom In</property>
                 <signal name="clicked" handler="on_zoom_in_clicked" swapped="true"/>
+                <style>
+                  <class name="osd"/>
+                </style>
                 <child>
                   <object class="GtkImage">
                     <property name="icon-name">zoom-in-symbolic</property>
@@ -49,6 +52,9 @@
               <object class="GtkButton">
                 <property name="tooltip-text">Zoom Out</property>
                 <signal name="clicked" handler="on_zoom_out_clicked" swapped="true"/>
+                <style>
+                  <class name="osd"/>
+                </style>
                 <child>
                   <object class="GtkImage">
                     <property name="icon-name">zoom-out-symbolic</property>