papercss/src/flexbox.scss

$columnNames: col, sm, md, lg;
$columnSizes: 0px, 768px, 992px, 1200px;

$numberOfColumns: 12;

@mixin make-column-class($name, $size, $n, $p: 1) when ($p =< $n)
{
    $percent: ($p * 100% / $n);
        .${name}-${p} {
            @include col-size($percent);
        }

    @include make-column-class($name, $size, $n, ($p + 1));
}

@mixin make-column-classes($n, $j: 1) when ($j =< length($columnNames))
{
    $columnName: extract($columnNames, $j);
    $columnSize: extract($columnSizes, $j);
    @media (min-width: $columnSize) {
        @include make-column-class($columnName, $columnSize, $n);
    }

    @include make-column-classes($n, $j + 1);
}

@mixin center-all()
{
    -webkit-align-items: center;
            align-items: center;
    -webkit-justify-content: center;
            justify-content: center;
}
@mixin col-size($percent)
{
    -webkit-box-flex: 0;
    -webkit-flex: 0 0 $percent;
    -ms-flex: 0 0 $percent;
    flex: 0 0 $percent;
    max-width: $percent;
}
.row {
    margin-right: auto;
    margin-left: auto;
    display: -webkit-box;
    display: -webkit-flex;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-orient: horizontal;
    -webkit-box-direction: normal;
    -webkit-flex-flow: row wrap;
    -ms-flex-flow: row wrap;
    flex-flow: row wrap;
    margin-bottom: 1rem;
    &.flex-right {
        -webkit-box-pack: end;
        -webkit-justify-content: flex-end;
        -ms-flex-pack: end;
        justify-content: flex-end;
    }
    &.flex-center {
        -webkit-box-pack: center;
        -webkit-justify-content: center;
        -ms-flex-pack: center;
        justify-content: center;
    }
    &.flex-edges {
        -webkit-box-pack: justify;
        -webkit-justify-content: space-between;
        -ms-flex-pack: justify;
        justify-content: space-between;
    }
    &.flex-spaces {
        -webkit-justify-content: space-around;
        -ms-flex-pack: distribute;
        justify-content: space-around;
    }
    &.flex-top {
        -webkit-box-align: start;
        -webkit-align-items: flex-start;
        -ms-flex-align: start;
        align-items: flex-start;
    }
    &.flex-middle {
        -webkit-box-align: center;
        -webkit-align-items: center;
        -ms-flex-align: center;
        align-items: center;
    }
    &.flex-bottom {
        -webkit-box-align: end;
        -webkit-align-items: flex-end;
        -ms-flex-align: end;
        align-items: flex-end;
    }
}
.col {
    padding: 1rem;
    @media (max-width: 767px) {
        // Stack for mobile
        @include col-size(100%);
    }
}
.col-fill {
    width: auto;
    flex: 1 1 0px;
}
@include make-column-classes($numberOfColumns);
.align-top {
    -webkit-align-self: flex-start;
    -ms-flex-item-align: start;
    align-self: flex-start;
}
.align-middle {
    -webkit-align-self: center;
    -ms-flex-item-align: center;
    -ms-grid-row-align: center;
    align-self: center;
}
.align-bottom {
    -webkit-align-self: flex-end;
    -ms-flex-item-align: end;
    align-self: flex-end;
}