[gtk/wip/chergert/fix-text-overdraw] css: reduce overdraws from "textview > text"

[Christian Hergert <chergert src gnome org>]

commit e38e8ed73e063c9f6a23c232582e058167d77204
Author: Christian Hergert <christian hergert me>
Date:   Fri Feb 11 23:02:20 2022 -0800

    css: reduce overdraws from "textview > text"
    
    This was causing us to draw the same background content twice which is a
    significant amount of bits to flip in the GPU for maximized windows,
    especially twice.

 gtk/theme/Default/_common.scss | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/gtk/theme/Default/_common.scss b/gtk/theme/Default/_common.scss
index 02af5e936c..27e75a2d52 100644
--- a/gtk/theme/Default/_common.scss
+++ b/gtk/theme/Default/_common.scss
@@ -66,6 +66,8 @@ textview {
   > text {
     @extend %view;
 
+    background-color: transparent;
+
     > selection {
       background-color: $backdrop_selected_bg_color;