diff --git a/src/librustdoc/html/static/rustdoc.css b/src/librustdoc/html/static/rustdoc.css
index c15051376bf..b1aac2da1c2 100644
--- a/src/librustdoc/html/static/rustdoc.css
+++ b/src/librustdoc/html/static/rustdoc.css
@@ -817,6 +817,7 @@ span.since {
 	position: absolute;
 	left: -1px;
 	margin-top: 7px;
+	z-index: 1;
 }
 
 .tooltip {
@@ -853,3 +854,7 @@ span.since {
 	border-style: solid;
 	border-color: transparent black transparent transparent;
 }
+
+pre.rust {
+	position: relative;
+}