Actually address accessibility issue

Author: bigtiger

partials/navigation.hbs

@@ -1,4 +1,4 @@
-{{#if isSecondary}}{{else}}<a href="/" class="logo-circle" alt="Home"></a>{{/if}}
+{{#if isSecondary}}{{else}}<a href="/" class="logo-circle"><span class="visually-hidden">Home</span></a>{{/if}}
 <ul class="nav">
   {{#foreach navigation}}
     <li class="nav-{{slug}}{{#if current}} nav-current{{/if}}">

src/css/layout/navigation.css

@@ -182,3 +182,15 @@ nav .menu-icon.close {
     width: 101.5%;
   }
 }
+
+.visually-hidden {
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  padding: 0;
+  margin: -1px;
+  overflow: hidden;
+  clip: rect(0, 0, 0, 0);
+  white-space: nowrap;
+  border: 0;
+}