sass-site/source/assets/stylesheets/regions/_navigation.scss

.navigation {
  margin: 0 #{-$gutter-width};
  @include padding-leader;
  background: $color-background;

  li {
    @include trailer(.5);

    &:last-child { margin-bottom: 0; }
  }

  a {
    @include padding-leader(.5);
    @include padding-trailer(.5);
    display: block;
    padding: {
      right: $gutter-width;
       left: $gutter-width;
    }
    background: mix($color-background, $color-background-shade);

    &:hover,
    &:focus { background: $color-background-shade; }
  }

  @include at-breakpoint($tablet-small) {
    margin: {
      right: 0;
       left: 0;
    }

    ul { @extend %clear-fix-tablet-small; }

    li {
      float: left;
      width: 50%;

      &:nth-child(odd) {
        clear: both;
        padding-right: $gutter-width / 2;
      }

      &:nth-child(even) { padding-left: $gutter-width / 2; }
    }
  }

  @include at-breakpoint($tablet-large) {
    @extend %table-cell-tablet-large;
     margin: 0;
    padding: 0;
    text-align: right;
    background: none;

    &.collapse { display: table-cell !important; }

    ul {
      display: inline-block;
      margin: 0 #{-$gutter-width} 0 $gutter-width;
    }

    li {
      margin: {
        right: $gutter-width;
        bottom: 0;
      }
      width: auto;

      &:nth-child(odd) {
        clear: none;
        padding-right: 0;
      }

      &:nth-child(even) { padding-left: 0;  }

      &:last-child { margin-right: 0; }
    }

    a {
      background: none;

      &:hover,
      &:focus { background: $color-background-shade; }
    }
  }
}