Added styles to grade out the top and bottom of the sidebar border and fixed spacing with the video and the sequence nav

common/lib/xmodule/xmodule/css/sequence/display.scss

@@ -4,7 +4,7 @@ nav.sequence-nav {
   @extend .topbar;
   border-bottom: 1px solid $border-color;
   @include border-top-right-radius(4px);
-  margin: (-(lh())) (-(lh())) lh() (-(lh()));
+  margin: 0 0 lh() (-(lh()));
   position: relative;
 
   ol {

common/lib/xmodule/xmodule/css/video/display.scss

@@ -4,7 +4,7 @@ div.video {
   border-bottom: 1px solid #e1e1e1;
   border-top: 1px solid #e1e1e1;
   display: block;
-  margin: 0 (-(lh()));
+  margin: 0 0 0 (-(lh()));
   padding: 6px lh();
 
   article.video-wrapper {