Make header responsive

_includes/base/top_nav.html

@@ -1,5 +1,5 @@
 <!-- Navigation -->
-<nav class="navbar sticky-top navbar-light bg-light flex-md-nowrap p-0 docsite-header">
+<nav class="navbar sticky-top navbar-light bg-light flex-md-nowrap docsite-header">
   <div class="container-fluid">
     <a class="navbar-brand" href="{{ site.baseurl }}/">
       <img src={{ "/images/rush-horiz.svg" | absolute_url }}

_sass/_docsite.scss

@@ -5,7 +5,13 @@
 }
 
 .docsite-header {
-  height: var(--docsite-header-size);
+  position: static;
+
+  @include media-breakpoint-up(md) {
+    position: sticky;
+    height: var(--docsite-header-size);
+    padding: 0;
+  }
 }
 
 .docsite-side-nav {