[libadwaita/wip/exalm/headers: 1/2] stylesheet: Fix treeview and columnview header borders

[Alexander Mikhaylenko <alexm src gnome org>]

commit 1933848cfec266b694ba3f47c0cdb4eaf1e2f04d
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Wed Oct 27 17:29:02 2021 +0500

    stylesheet: Fix treeview and columnview header borders
    
    Fixes https://gitlab.gnome.org/GNOME/libadwaita/-/issues/175

 src/stylesheet/widgets/_trees.scss | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)
---
diff --git a/src/stylesheet/widgets/_trees.scss b/src/stylesheet/widgets/_trees.scss
index 1d331dfb..46a1ccc7 100644
--- a/src/stylesheet/widgets/_trees.scss
+++ b/src/stylesheet/widgets/_trees.scss
@@ -70,16 +70,14 @@ treeview.view {
     > button {
       @extend %undecorated_button;
       padding: 0 6px;
-      border: 1px solid gtkalpha($view_fg_color, .15);
-      border-width: 0 0 1px 1px;
+      border: 0px solid gtkalpha($view_fg_color, .15);
+      border-bottom-width: 1px;
       border-radius: 0;
 
       &:disabled {
         border-color: $window_bg_color;
       }
 
-      &:last-child { border-right-width: 0; }
-
       color: gtkalpha($view_fg_color, .4);
       font-weight: bold;
       box-shadow: none;
@@ -126,6 +124,24 @@ treeview.view {
   }
 }
 
+// Buttons slightly differ between treeviews and columnviews
+treeview.view > header > button {
+  border-right-width: 1px;
+
+  &:last-child:dir(ltr),
+  &:first-child:dir(rtl) {
+    border-right-width: 0;
+  }
+}
+
+columnview.view > header > button {
+  border-left-width: 1px;
+
+  &:first-child {
+    border-left-width: 0;
+  }
+}
+
 /********************************************************
  * Data Tables                                          *
  * treeview like tables with individual focusable cells *