print dialog: Stop using action_box in .ui

We can just use CSS margins nowadays to achieve the desired
appearance.

gtk/theme/Adwaita/_common.scss

@@ -2739,6 +2739,23 @@ levelbar {
   }
 }
 
+/****************
+ * Print dialog *
+*****************/
+
+printdialog {
+  paper {
+    border: 1px solid $borders_color;
+    background: white;
+    padding: 0;
+
+    &:backdrop { border-color: $backdrop_borders_color; }
+  }
+
+  .dialog-action-box {
+    margin: 12px;
+  }
+}
 
 /**********
  * Frames *
@@ -2756,14 +2773,6 @@ frame border,
   &:backdrop { border-color: $backdrop_borders_color; }
 }
 
-paper {
-  border: 1px solid $borders_color;
-  background: white;
-  padding: 0;
-
-  &:backdrop { border-color: $backdrop_borders_color; }
-}
-
 actionbar box {
   padding: 6px;
   border-width: 1px 0 0;

gtk/theme/Adwaita/gtk-contained-dark.css

@@ -3610,6 +3610,18 @@ levelbar {
     levelbar block.empty:backdrop {
       border-color: rgba(148, 151, 150, 0.15); }
 
+/****************
+ * Print dialog *
+*****************/
+printdialog paper {
+  border: 1px solid #1c1f1f;
+  background: white;
+  padding: 0; }
+  printdialog paper:backdrop {
+    border-color: #1f2222; }
+printdialog .dialog-action-box {
+  margin: 12px; }
+
 /**********
  * Frames *
  **********/
@@ -3627,13 +3639,6 @@ frame border,
   .frame:backdrop {
     border-color: #1f2222; }
 
-paper {
-  border: 1px solid #1c1f1f;
-  background: white;
-  padding: 0; }
-  paper:backdrop {
-    border-color: #1f2222; }
-
 actionbar box {
   padding: 6px;
   border-width: 1px 0 0; }

gtk/theme/Adwaita/gtk-contained.css

@@ -3743,6 +3743,18 @@ levelbar {
     levelbar block.empty:backdrop {
       border-color: rgba(139, 142, 143, 0.15); }
 
+/****************
+ * Print dialog *
+*****************/
+printdialog paper {
+  border: 1px solid #9d9d99;
+  background: white;
+  padding: 0; }
+  printdialog paper:backdrop {
+    border-color: #a5a5a1; }
+printdialog .dialog-action-box {
+  margin: 12px; }
+
 /**********
  * Frames *
  **********/
@@ -3760,13 +3772,6 @@ frame border,
   .frame:backdrop {
     border-color: #a5a5a1; }
 
-paper {
-  border: 1px solid #9d9d99;
-  background: white;
-  padding: 0; }
-  paper:backdrop {
-    border-color: #a5a5a1; }
-
 actionbar box {
   padding: 6px;
   border-width: 1px 0 0; }

gtk/ui/gtkprintunixdialog.ui

@@ -60,11 +60,6 @@
         <style>
           <class name="view"/>
         </style>
-        <child internal-child="action_box">
-          <object class="GtkBox">
-            <property name="margin">6</property>
-          </object>
-        </child>
         <child>
           <object class="GtkBox" id="box1">
             <property name="visible">1</property>