[five-or-more] Adapt to StyleContext API.

[Arnaud B. <arnaudb src gnome org>]

commit 44229841421b930fd5f124b4fcbb9af1ddb57619
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Fri Mar 13 10:19:18 2020 +0100

    Adapt to StyleContext API.
    
    TODO test.

 src/view.vala | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/src/view.vala b/src/view.vala
index ef9c203..c572212 100644
--- a/src/view.vala
+++ b/src/view.vala
@@ -335,8 +335,7 @@ private class View : DrawingArea
 
     private void draw_gridlines (Cairo.Context cr)
     {
-        Gdk.RGBA grid_color = cs.get_color (cs.get_state ());
-        Gdk.cairo_set_source_rgba (cr, grid_color);
+        cr.set_source_rgba (0.0, 0.0, 0.0, 0.8);
         cr.set_line_width (1.0);
 
         for (int i = piece_size; i < board_rectangle.width; i += piece_size)
@@ -356,6 +355,7 @@ private class View : DrawingArea
         border.width = board_rectangle.width;
         border.height = board_rectangle.height;
 
+        cr.set_source_rgba (0.0, 0.0, 0.0, 1.0);
         Gdk.cairo_rectangle (cr, border);
         cr.stroke ();
     }
@@ -364,7 +364,7 @@ private class View : DrawingArea
     {
         if (show_cursor)
         {
-            Gdk.RGBA grid_color = cs.get_color (cs.get_state ());
+            Gdk.RGBA grid_color = cs.get_color ();
             Gdk.cairo_set_source_rgba (cr, grid_color);
             cr.set_line_width (2.0);