[gnome-builder] map: tweak font sizing

[Christian Hergert <chergert src gnome org>]

commit e0e1537c2faf20c6149c50a4c1cf19bf3d77c66c
Author: Christian Hergert <chergert redhat com>
Date:   Thu Nov 18 12:02:37 2021 -0800

    map: tweak font sizing
    
    This is closer to what we do in GtkSourceView 5.x by default.

 src/libide/themes/themes/shared/shared-editor.css | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/src/libide/themes/themes/shared/shared-editor.css 
b/src/libide/themes/themes/shared/shared-editor.css
index 6b0a0dc39..c42d86e39 100644
--- a/src/libide/themes/themes/shared/shared-editor.css
+++ b/src/libide/themes/themes/shared/shared-editor.css
@@ -149,7 +149,9 @@ vte-terminal {
 }
 
 textview.source-map {
-  font-size: 2px;
+  font-size: 1.75pt;
+  /* we can't do the following in GTK 3, but supported in 4.4 */
+  /* line-height: 4px; */
 }
 textview.source-map .scrubber {
   border-radius: 5px;