doc: add links to alternative versions of doc

Each page of the API documentation should have links to other versions
of the same page. This will make it easier to switch between the current
"live" release at nodejs.org and LTS versions.

PR-URL: https://github.com/nodejs/node/pull/10958
Fixes: https://github.com/nodejs/node/issues/10726
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

1 files changed, 58 insertions, 0 deletions

diff --git a/doc/api_assets/style.css b/doc/api_assets/style.css
index 3761be4031e..6d764fd8891 100644
--- a/doc/api_assets/style.css
+++ b/doc/api_assets/style.css
@@ -81,6 +81,61 @@ em code {
 
 #gtoc {
   font-size: .8em;
+  margin-bottom: 1em;
+}
+
+#gtoc ul {
+  list-style: none;
+  margin-left: 0;
+}
+
+#gtoc li {
+  display: inline;
+}
+
+li.version-picker {
+  position: relative;
+}
+
+li.version-picker:hover > ol {
+  display: block;
+}
+
+li.version-picker a span {
+  font-size: .7em;
+}
+
+ol.version-picker {
+  background: #fff;
+  border: 1px #43853d solid;
+  border-radius: 2px;
+  display: none;
+  list-style: none;
+  position: absolute;
+  right: -2px;
+  width: 101%;
+}
+
+#gtoc ol.version-picker li {
+  display: block;
+}
+
+ol.version-picker li a {
+  border-radius: 0;
+  display: block;
+  margin: 0;
+  padding: .1em;
+  padding-left: 1em;
+}
+
+ol.version-picker li:first-child a {
+  border-top-right-radius: 1px;
+  border-top-left-radius: 1px;
+}
+
+ol.version-picker li:last-child a {
+  border-bottom-right-radius: 1px;
+  border-bottom-left-radius: 1px;
 }
 
 .line {
@@ -507,6 +562,9 @@ th > *:last-child, td > *:last-child {
   #content {
     font-size: 3.5em;
   }
+  #gtoc {
+    font-size: 0.6em;
+  }
 }
 
 @media print {