Issue 173 fix (alshedivat#178)

* Changed color of icon from static to using variable.

Author: JD

_includes/header.html

@@ -13,7 +13,7 @@
           {% include social.html %}
         </div>
       {% endif %}
-      <!-- Navbar Toogle -->
+      <!-- Navbar Toggle -->
       <button class="navbar-toggler collapsed ml-auto" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
         <span class="sr-only">Toggle navigation</span>
         <span class="icon-bar top-bar"></span>

_sass/_base.scss

@@ -123,7 +123,7 @@ a, table.table a {
     display: block;
     width: 22px;
     height: 2px;
-    background-color: $grey-color-dark;
+    background-color: var(--global-icon-color);
     border-radius: 1px;
     margin-bottom: 4px;
     transition: all 0.2s;