diff --git a/doc/assets/style.css b/doc/assets/style.css
index e3c6f35..27677fd 100644
--- a/doc/assets/style.css
+++ b/doc/assets/style.css
@@ -128,7 +128,7 @@ div.doc-toc {
     bottom: 0px;
     border-right: 1px solid #c9c9c9;
     padding-top: 10px;
-    box-shadow: 2px 0px 7px #878887;
+    box-shadow: 0px 3px 6px 0px rgba(0,0,0,0.65);
     z-index: 20;
 }
 button#btn_toc {