Flexbox columns

.cols-container {
  display: flex;
  flex-flow: row wrap;
  margin-left: calc(var(--inner-gutter) * -1);
}

  @media (min-width: 429px)
:root {
  --breakpoint: "sm";
  --container-width: unset;
  --inner-gutter: 16px;
  --outer-gutter: 16px;
  --grid-columns: 6;
}

.container {
  width: calc(var(--container-width, 100%) - (2 * var(--outer-gutter, 0)));
  margin-right: auto;
  margin-left: var(--outer-gutter);
}