refactors some of the sequence nav styles

static/css/application.css

@@ -3567,19 +3567,15 @@ div.course-wrapper.closed section.course-content div.video-subtitles ol.subtitle
   max-height: 577px; }
 
 nav.sequence-nav {
-  -webkit-box-sizing: border-box;
-  -moz-box-sizing: border-box;
-  box-sizing: border-box;
+  border-bottom: 1px solid #e4d080;
   margin-bottom: 22.652px;
-  position: relative;
-  top: -1px; }
+  position: relative; }
 nav.sequence-nav ol {
-  border-bottom: 1px solid #e4d080;
-  border-top: 1px solid #e4d080;
   -webkit-box-sizing: border-box;
   -moz-box-sizing: border-box;
   box-sizing: border-box;
   display: table;
+  height: 100%;
   padding-right: 8.696%;
   width: 100%; }
 nav.sequence-nav ol li {
@@ -3722,8 +3718,8 @@ nav.sequence-nav ol li a:hover p {
   margin-top: 4px;
   opacity: 1; }
 nav.sequence-nav ul {
-  margin-right: 1px;
   list-style: none !important;
+  height: 100%;
   position: absolute;
   right: 0;
   top: 0;

templates/sass/courseware/_sequence-nav.scss

 nav.sequence-nav {
   @extend .topbar;
-  @include box-sizing(border-box);
+  border-bottom: 1px solid darken($cream, 20%);
   margin-bottom: $body-line-height;
   position: relative;
-  top: -1px;
 
   ol {
-    border-bottom: 1px solid darken($cream, 20%);
-    border-top: 1px solid darken($cream, 20%);
     @include box-sizing(border-box);
     display: table;
+    height: 100%;
     padding-right: flex-grid(1, 9);
     width: 100%;
 
@@ -172,8 +170,8 @@ nav.sequence-nav {
   }
 
   ul {
-    margin-right: 1px;
     list-style: none !important;
+    height: 100%;
     position: absolute;
     right: 0;
     top: 0;