diff --git a/docs/manual/style/css/manual.css b/docs/manual/style/css/manual.css
index b3b024d46f..4b26751579 100644
--- a/docs/manual/style/css/manual.css
+++ b/docs/manual/style/css/manual.css
@@ -1032,6 +1032,24 @@ p.figure dfn {
     font-weight: bold;
 }
 
+/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ * Permalink are used in <h2> tags only.
+ * They are hidden by default, and become visible only when the mouse
+ * is over the corresponding element.
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
+.permalink {
+    visibility: hidden;
+}
+.permalink:link {
+   color: white;
+}
+.permalink:visited {
+   color: white;
+}
+h2:hover > .permalink {
+    visibility: visible;
+}
+
 /* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  * -> The End <-
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */