diff --git a/theme-arc-blue.css b/theme-arc-blue.css
index 4417d63..aa626a8 100644
--- a/theme-arc-blue.css
+++ b/theme-arc-blue.css
@@ -899,7 +899,9 @@
       background: #060639;
       padding: 7px;
   }
-  /* Checkbox element, when checked */
+  .repository .diff-detail-box ol li {
+      background: #0a0a0a;
+  }  /* Checkbox element, when checked */
   input[type="checkbox"]:checked {
       box-shadow: 0 0 0 2px #acacac;
   }