Expand on nav_list styles

- Consolidate SCSS partials

_includes/nav_list

@@ -1,20 +1,20 @@
 {% include base_path %}
 {% assign navigation = site.data.navigation[page.sidebar.nav] %}
 
-<nav>
+<nav class="nav__list">
   <ul>
     {% for nav in navigation %}
-      <li>{{ nav.title }}
+      <li><span class="nav__sub-title">{{ nav.title }}</span>
         {% if nav.children != null %}
         <ul>
           {% for child in nav.children %}
             {% assign nav_url = child.path | prepend: "/" | prepend: page.sidebar.nav | prepend: "/" | append: "/" | prepend: base_path %}
             {% if nav_url contains page.url %}
-              {% assign c = "current" %}
+              {% assign active = "active" %}
             {% else %}
-              {% assign c = "" %}
+              {% assign active = "" %}
             {% endif %}
-            <li><a href="{{ nav_url }}" class="{{ c }}">{{ child.title }}</a></li>
+            <li><a href="{{ nav_url }}" class="{{ active }}">{{ child.title }}</a></li>
           {% endfor %}
         </ul>
         {% endif %}

_includes/sidebar.html

@@ -16,7 +16,7 @@
       {% if s.text %}{{ s.text | markdownify }}{% endif %}
     {% endfor %}
     {% if page.sidebar.nav %}
-      {% include nav_list.html items=page.sidebar.nav %}
+      {% include nav_list items=page.sidebar.nav %}
     {% endif %}
   {% endif %}
   </div>

_includes/toc

@@ -1,6 +1,6 @@
 <aside class="sidebar__right">
 <nav class="toc" markdown="1">
-<header><h4 class="toc__title"><i class="fa fa-{{ include.icon | default: 'book' }}"></i> {{ include.title | default: site.data.ui-text[site.locale].toc_label }}</h4></header>
+<header><h4 class="nav__title"><i class="fa fa-{{ include.icon | default: 'book' }}"></i> {{ include.title | default: site.data.ui-text[site.locale].toc_label }}</h4></header>
 *  Auto generated table of contents
 {:toc .toc__menu}
 </nav>