Update sidebar.html

Author: jonrohan

includes/sidebar.html

@@ -1,7 +1,7 @@
 <!-- product > category > maptopic > article -->
 <div class="sidebar d-none d-lg-block">
 
-  <div class="d-flex flex-items-center p-4 position-sticky top-0" style="z-index: 3;" id="github-logo">
+  <div class="d-flex flex-items-center p-4 position-sticky top-0 sidebar-background-color" style="z-index: 3;" id="github-logo">
     <a href="/{{ currentLanguage }}" class="text-white" aria-hidden="true">
       {% octicon "mark-github" height="32" %}
     </a>