diff --git a/book/source/_static/html/css/custom.css b/book/source/_static/html/css/custom.css
index a2bd3de..ec0eaff 100644
--- a/book/source/_static/html/css/custom.css
+++ b/book/source/_static/html/css/custom.css
@@ -46,3 +46,12 @@ span.std-term {
   color: rgb(62, 67, 73);
   border-bottom: 1px dotted rgb(62, 67, 73);
 }
+
+/*
+Footnote list
+*/
+aside.footnote-list {
+  border-top: 1px solid black;
+  margin-top: 2em;
+  padding-top: 2em;
+}
\ No newline at end of file