Basic CSS grid built with flex which supports a large and small breakpoint.

flex_grid.scss

//* Flex Container and Margins
.row {
  box-sizing: border-box;
  display: flex;
  flex: 0 1 auto;
  -ms-flex-direction: row;
  flex-direction: row;
  -ms-flex-wrap: wrap;
  flex-wrap: wrap;
  margin-right: -1rem;
  margin-left: -1rem;
}

//* Extra Small Devices
.col-extra-small,
.col-extra-small-1,
.col-extra-small-2,
.col-extra-small-3,
.col-extra-small-4,
.col-extra-small-5,
.col-extra-small-6,
.col-extra-small-7,
.col-extra-small-8,
.col-extra-small-9,
.col-extra-small-10,
.col-extra-small-11,
.col-extra-small-12 {
  box-sizing: border-box;
  -ms-flex: 0 0 auto;
  flex: 0 0 auto;
  padding-right: 1rem;
  padding-left: 1rem;
}

.col-extra-small {
  -webkit-flex-grow: 1;
  -ms-flex-positive: 1;
  flex-grow: 1;
  -ms-flex-preferred-size: 0;
  flex-basis: 0;
  max-width: 100%;
}

.col-extra-small-1 {
  -ms-flex-preferred-size: 8.333%;
  flex-basis: 8.333%;
  max-width: 8.333%;
}

.col-extra-small-2 {
  -ms-flex-preferred-size: 16.667%;
  flex-basis: 16.667%;
  max-width: 16.667%;
}

.col-extra-small-3 {
  -ms-flex-preferred-size: 25%;
  flex-basis: 25%;
  max-width: 25%;
}

.col-extra-small-4 {
  -ms-flex-preferred-size: 33.333%;
  flex-basis: 33.333%;
  max-width: 33.333%;
}

.col-extra-small-5 {
  -ms-flex-preferred-size: 41.667%;
  flex-basis: 41.667%;
  max-width: 41.667%;
}

.col-extra-small-6 {
  -ms-flex-preferred-size: 50%;
  flex-basis: 50%;
  max-width: 50%;
}

.col-extra-small-7 {
  -ms-flex-preferred-size: 58.333%;
  flex-basis: 58.333%;
  max-width: 58.333%;
}

.col-extra-small-8 {
  -ms-flex-preferred-size: 66.667%;
  flex-basis: 66.667%;
  max-width: 66.667%;
}

.col-extra-small-9 {
  -ms-flex-preferred-size: 75%;
  flex-basis: 75%;
  max-width: 75%;
}

.col-extra-small-10 {
  -ms-flex-preferred-size: 83.333%;
  flex-basis: 83.333%;
  max-width: 83.333%;
}

.col-extra-small-11 {
  -ms-flex-preferred-size: 91.667%;
  flex-basis: 91.667%;
  max-width: 91.667%;
}

.col-extra-small-12 {
  -ms-flex-preferred-size: 100%;
  flex-basis: 100%;
  max-width: 100%;
}

.col-extra-small-offset-1 {
  margin-left: 8.333%;
}

.col-extra-small-offset-2 {
  margin-left: 16.667%;
}

.col-extra-small-offset-3 {
  margin-left: 25%;
}

.col-extra-small-offset-4 {
  margin-left: 33.333%;
}

.col-extra-small-offset-5 {
  margin-left: 41.667%;
}

.col-extra-small-offset-6 {
  margin-left: 50%;
}

.col-extra-small-offset-7 {
  margin-left: 58.333%;
}

.col-extra-small-offset-8 {
  margin-left: 66.667%;
}

.col-extra-small-offset-9 {
  margin-left: 75%;
}

.col-extra-small-offset-10 {
  margin-left: 83.333%;
}

.col-extra-small-offset-11 {
  margin-left: 91.667%;
}

//* Small Devices
@media only screen and (min-width: 48em) {
  .col-small,
  .col-small-1,
  .col-small-2,
  .col-small-3,
  .col-small-4,
  .col-small-5,
  .col-small-6,
  .col-small-7,
  .col-small-8,
  .col-small-9,
  .col-small-10,
  .col-small-11,
  .col-small-12 {
    box-sizing: border-box;
    -ms-flex: 0 0 auto;
    flex: 0 0 auto;
    padding-right: 1rem;
    padding-left: 1rem;
  }

  .col-small {
    -webkit-flex-grow: 1;
    -ms-flex-positive: 1;
    flex-grow: 1;
    -ms-flex-preferred-size: 0;
    flex-basis: 0;
    max-width: 100%;
  }

  .col-small-1 {
    -ms-flex-preferred-size: 8.333%;
    flex-basis: 8.333%;
    max-width: 8.333%;
  }

  .col-small-2 {
    -ms-flex-preferred-size: 16.667%;
    flex-basis: 16.667%;
    max-width: 16.667%;
  }

  .col-small-3 {
    -ms-flex-preferred-size: 25%;
    flex-basis: 25%;
    max-width: 25%;
  }

  .col-small-4 {
    -ms-flex-preferred-size: 33.333%;
    flex-basis: 33.333%;
    max-width: 33.333%;
  }

  .col-small-5 {
    -ms-flex-preferred-size: 41.667%;
    flex-basis: 41.667%;
    max-width: 41.667%;
  }

  .col-small-6 {
    -ms-flex-preferred-size: 50%;
    flex-basis: 50%;
    max-width: 50%;
  }

  .col-small-7 {
    -ms-flex-preferred-size: 58.333%;
    flex-basis: 58.333%;
    max-width: 58.333%;
  }

  .col-small-8 {
    -ms-flex-preferred-size: 66.667%;
    flex-basis: 66.667%;
    max-width: 66.667%;
  }

  .col-small-9 {
    -ms-flex-preferred-size: 75%;
    flex-basis: 75%;
    max-width: 75%;
  }

  .col-small-10 {
    -ms-flex-preferred-size: 83.333%;
    flex-basis: 83.333%;
    max-width: 83.333%;
  }

  .col-small-11 {
    -ms-flex-preferred-size: 91.667%;
    flex-basis: 91.667%;
    max-width: 91.667%;
  }

  .col-small-12 {
    -ms-flex-preferred-size: 100%;
    flex-basis: 100%;
    max-width: 100%;
  }

  .col-small-offset-1 {
    margin-left: 8.333%;
  }

  .col-small-offset-2 {
    margin-left: 16.667%;
  }

  .col-small-offset-3 {
    margin-left: 25%;
  }

  .col-small-offset-4 {
    margin-left: 33.333%;
  }

  .col-small-offset-5 {
    margin-left: 41.667%;
  }

  .col-small-offset-6 {
    margin-left: 50%;
  }

  .col-small-offset-7 {
    margin-left: 58.333%;
  }

  .col-small-offset-8 {
    margin-left: 66.667%;
  }

  .col-small-offset-9 {
    margin-left: 75%;
  }

  .col-small-offset-10 {
    margin-left: 83.333%;
  }

  .col-small-offset-11 {
    margin-left: 91.667%;
  }
}