Style fixes for tools & 404 page:

- Set Bootstrap colors for background colors
- Adjust button padding to work in more contexts
- Removed unused tool CSS. Migrated some styles to SCSS.
- Fix sticky overlap in faucets sidebar
- Make 404 page inherit from base template

tool/template-doc.html

@@ -34,7 +34,7 @@
     <div class="card-header">
       <h4>{% trans %}In this document{% endtrans %}</h4>
     </div>
-    <ul class="card-body">
+    <ul class="card-body page-toc">
       {{ sidebar_content }}
     </ul>
   </div>