diff --git a/themes/atom-dark-ui/package.cson b/themes/atom-dark-ui/package.cson
index ece0b95aa..2fd3e43f1 100644
--- a/themes/atom-dark-ui/package.cson
+++ b/themes/atom-dark-ui/package.cson
@@ -7,6 +7,7 @@
   'loading'
   'buttons'
   'panels'
+  'panes'
   'lists'
   'editor'
   'tabs'
diff --git a/themes/atom-dark-ui/panes.less b/themes/atom-dark-ui/panes.less
new file mode 100644
index 000000000..b61770403
--- /dev/null
+++ b/themes/atom-dark-ui/panes.less
@@ -0,0 +1,9 @@
+@import "ui-mixins";
+@import "ui-variables";
+@import "buttons";
+
+.pane-item {
+  .panel {
+    border-color: fadeout(@inset-panel-border-color, 30%);
+  }
+}