[gnome-builder/wip/gtk4-port: 352/736] libide-editor: add style css for overview map

[Christian Hergert <chergert src gnome org>]

commit 465fa2590fc88f1ffdf09c318e136464a1d0ccd7
Author: Christian Hergert <chergert redhat com>
Date:   Sat Apr 2 11:58:46 2022 -0700

    libide-editor: add style css for overview map

 src/libide/editor/libide-editor.gresource.xml |  1 +
 src/libide/editor/style.css                   | 12 ++++++++++++
 2 files changed, 13 insertions(+)
---
diff --git a/src/libide/editor/libide-editor.gresource.xml b/src/libide/editor/libide-editor.gresource.xml
index 722b752b5..10cd2084c 100644
--- a/src/libide/editor/libide-editor.gresource.xml
+++ b/src/libide/editor/libide-editor.gresource.xml
@@ -2,5 +2,6 @@
 <gresources>
   <gresource prefix="/org/gnome/libide-editor/">
     <file preprocess="xml-stripblanks">ide-editor-page.ui</file>
+    <file>style.css</file>
   </gresource>
 </gresources>
diff --git a/src/libide/editor/style.css b/src/libide/editor/style.css
new file mode 100644
index 000000000..d958de97d
--- /dev/null
+++ b/src/libide/editor/style.css
@@ -0,0 +1,12 @@
+textview.GtkSourceMap {
+  font-family: BuilderBlocks;
+  font-size: 1.75pt;
+  line-height: 5px;
+  color: alpha(currentColor, 0.75);
+}
+textview.GtkSourceMap:dir(ltr) {
+  border-left: 1px solid @borders;
+}
+textview.GtkSourceMap:dir(rtl) {
+  border-right: 1px solid @borders;
+}