formspree/formspree/static/scss/grid.scss

.row {
    width: 100%;
    &:after {
        content: ".";
        display: block;
        clear: both;
        visibility: hidden;
        line-height: 0;
        height: 0;
    }
}

.container {
    max-width: 950px;
    margin: 0 auto;

    &:after {
        content: ".";
        display: block;
        clear: both;
        visibility: hidden;
        line-height: 0;
        height: 0;
    }

    &.narrow {
        @media (min-width: 760px) {
            max-width: 600px;
        }
    }

    @media (max-width: 760px) {
        max-width: 100% !important;
    }
}

@mixin col {
    float: left;
    padding: 0 20px;

    @media (max-width: 760px) {
      width: 100% !important;
      margin-bottom: 20px !important;
    }

}

.col-1-1 {
    @include col;
    width: 100%;
}

.col-1-2 {
    @include col;
    width: 50%;
}

.col-1-3 {
    @include col;
    width: 33.33%;
}

.col-2-3 {
    @include col;
    width: 66.66%;
}

.col-1-4 {
    @include col;
    width: 25%;
}

.col-3-4 {
    @include col;
    width: 75%;
}

.col-2-5 {
    @include col;
    width: 40%;
}

.col-3-5 {
    @include col;
    width: 60%;
}