fixed padding issue on seq nav

lms/static/sass/courseware/_sequence-nav.scss

@@ -11,6 +11,7 @@ nav.sequence-nav {
     height: 100%;
     padding-right: flex-grid(1, 9);
     width: 100%;
+    padding-left: 0;
 
     a {
       @extend .block-link;
@@ -279,6 +280,7 @@ section.course-content {
       @include border-radius(3px);
       @include box-shadow(inset 0 0 0 1px lighten(#f6efd4, 5%));
       @include inline-block();
+      padding-left: 0;
 
       li {
         float: left;