diff --git a/networking/osi_model/osi_model_assets/osi_model.css b/networking/osi_model/osi_model_assets/osi_model.css
index d42ad52..a28b192 100644
--- a/networking/osi_model/osi_model_assets/osi_model.css
+++ b/networking/osi_model/osi_model_assets/osi_model.css
@@ -4,4 +4,13 @@
 
 .osiContent {
     font-family: arvo;
+}
+
+summary {
+  list-style-image: url(arrow.png);
+}
+
+summary::-webkit-details-marker {
+  background: url(arrow.png);
+  color: transparent;
 }
\ No newline at end of file