LMS: fixing skip links and adding a11y tests

cms/static/sass/_base.scss

@@ -648,21 +648,22 @@ hr.divider {
 // ui - skipnav
 .nav-skip {
   @extend %t-action3;
-  display: block;
+  display: inline-block;
   position: absolute;
   left: 0px;
   top: -($baseline*30);
-  width: 1px;
-  height: 1px;
   overflow: hidden;
   background: $white;
   border-bottom: 1px solid $gray-l4;
   padding: ($baseline*0.75) ($baseline/2);
 
-  &:focus, &:active {
-    position: static;
+  &:focus,
+  &:active {
+    position: relative;
+    top: auto;
     width: auto;
     height: auto;
+    margin: 0;
   }
 }
 
@@ -725,4 +726,3 @@ hr.divider {
     color: $gray-l1;
   }
 }
-

cms/static/sass/elements/_navigation.scss

@@ -25,21 +25,22 @@ nav {
 // skip navigation
 .nav-skip {
   @include font-size(13);
-  display: block;
+  display: inline-block;
   position: absolute;
   left: 0px;
   top: -($baseline*30);
-  width: 1px;
-  height: 1px;
   overflow: hidden;
   background: $white;
   border-bottom: 1px solid $gray-l4;
   padding: ($baseline*0.75) ($baseline/2);
 
-  &:focus, &:active {
-    position: static;
+  &:focus,
+  &:active {
+    position: relative;
+    top: auto;
     width: auto;
     height: auto;
+    margin: 0;
   }
 }
 

cms/templates/base.html

@@ -62,7 +62,7 @@ from openedx.core.djangolib.js_utils import (
       <%block name="page_alert"></%block>
       </div>
 
-      <div id="content">
+      <div id="content" tabindex="-1">
       <%block name="content"></%block>
       </div>
 

cms/templates/course-create-rerun.html

@@ -21,7 +21,7 @@ from django.template.defaultfilters import escapejs
 </%block>
 
 <%block name="content">
-<div id="content">
+<div id="content" tabindex="-1">
   <div class="wrapper-mast wrapper">
     <header class="mast mast-wizard has-actions">
       <h1 class="page-header">