@mixin grid-container($props...) {
  @if length($props) ==0 {
    @include u-margin-x(auto);
    @include u-maxw($theme-grid-container-max-width);
  } @else {
    $props: nth($props, 1);
    $margin-x: append-important($props, auto);
    @include u-margin-x($margin-x);
    @include u-maxw($props);
  }

  @include add-responsive-site-margins;
  @include this-border-box-sizing;
}