Fix top menu items not highlighted.

assets/css/styles.css

@@ -10,11 +10,10 @@ body, html {
     line-height:1.3em;
 }
 
-body#index a#indexnav,
-body#download a#downloadnav,
-body#how a#hownav,
-body#about a#aboutnav,
-body#involved a#involvednav {color:#87C214;}
+#nav #is-active {
+  color: #87C214;
+}
+
 
 #wrapper {
     min-height:100%;

themes/briar/layouts/partials/header.html

@@ -24,9 +24,11 @@
           <label for="menu-toggle"><img src="/img/menu.png" alt="Drop-down menu"></label>
           <input type="checkbox" id="menu-toggle"/>
           <ul id="menu">
+          {{ $currentPage := . }}
           {{ range .Site.Menus.main }}
           <li>
-          <a id="{{ .Identifier }}nav" href="{{ .URL }}">{{ .Name }}</a>
+          <a {{ if eq $currentPage.URL .URL }}id="is-active"{{end}}
+             href="{{ .URL }}">{{ .Name }}</a>
           </li>
           {{ end }}
           </ul>