Bootstrap 4 Flex Grid

index.scss

/*!
 * Bootstrap Grid v4.4.1 (https://getbootstrap.com/)
 * Copyright 2011-2019 The Bootstrap Authors
 * Copyright 2011-2019 Twitter, Inc.
 * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
 */

$grid-columns: 12 !default;
$grid-row-columns: 6 !default;
$grid-gutter-width: 30px !default;
$grid-breakpoints: (
  xs: 0,
  sm: 576px,
  md: 768px,
  lg: 992px,
  xl: 1200px
) !default;

$container-padding-x: $grid-gutter-width / 2 !default;
$container-max-widths: (
  sm: 540px,
  md: 720px,
  lg: 960px,
  xl: 1140px
) !default;

html {
  box-sizing: border-box;
  -ms-overflow-style: scrollbar;
}

*,
*::before,
*::after {
  box-sizing: inherit;
}

// Minimum breakpoint width. Null for the smallest (first) breakpoint.
@function breakpoint-min($name, $breakpoints: $grid-breakpoints) {
  $min: map-get($breakpoints, $name);
  @return if($min != 0, $min, null);
}

// Returns a blank string if smallest breakpoint, otherwise returns the name with a dash in front.
@function breakpoint-infix($name, $breakpoints: $grid-breakpoints) {
  @return if(breakpoint-min($name, $breakpoints) == null, "", "-#{$name}");
}

// Media of at least the minimum breakpoint width. No query for the smallest breakpoint.
// Makes the @content apply to the given breakpoint and wider.
@mixin media-breakpoint-up($name, $breakpoints: $grid-breakpoints) {
  $min: breakpoint-min($name, $breakpoints);
  @if $min {
    @media (min-width: $min) {
      @content;
    }
  } @else {
    @content;
  }
}

@mixin make-container($padding-x: $container-padding-x) {
  width: 100%;
  padding-right: $padding-x;
  padding-left: $padding-x;
  margin-right: auto;
  margin-left: auto;
}

// For each breakpoint, define the maximum width of the container in a media query
@mixin make-container-max-widths($max-widths: $container-max-widths, $breakpoints: $grid-breakpoints) {
  @each $breakpoint, $container-max-width in $max-widths {
    @include media-breakpoint-up($breakpoint, $breakpoints) {
      max-width: $container-max-width;
    }
  }
}

@mixin make-row($gutter: $grid-gutter-width) {
  display: flex;
  flex-wrap: wrap;
  margin-right: -$gutter / 2;
  margin-left: -$gutter / 2;
}

// Specify on a parent element(e.g., .row) to force immediate children into N number of columns.
// Supports wrapping to new lines, but does not do a Masonry style grid.
@mixin row-cols($count) {
  & > * {
    flex: 0 0 100% / $count;
    max-width: 100% / $count;
  }
}

@mixin make-col-auto() {
  flex: 0 0 auto;
  width: auto;
  max-width: 100%; // Reset earlier grid tiers
}

@mixin make-col($size, $columns: $grid-columns) {
  flex: 0 0 percentage($size / $columns);
  // Add a `max-width` to ensure content within each column does not blow out the width of the column.
  // Applies to IE10+ and Firefox.
  // Chrome and Safari do not appear to require this.
  max-width: percentage($size / $columns);
}

@mixin make-col-offset($size, $columns: $grid-columns) {
  $num: $size / $columns;
  margin-left: if($num == 0, 0, percentage($num));
}

// Used only by Bootstrap to generate the correct number of grid classes given any value of `$grid-columns`.
@mixin make-grid-columns($columns: $grid-columns, $gutter: $grid-gutter-width, $breakpoints: $grid-breakpoints) {
  // Common properties for all breakpoints
  %grid-column {
    position: relative;
    width: 100%;
    padding-right: $gutter / 2;
    padding-left: $gutter / 2;
  }

  @each $breakpoint in map-keys($breakpoints) {
    $infix: breakpoint-infix($breakpoint, $breakpoints);

    // Allow columns to stretch full width below their breakpoints
    @for $i from 1 through $columns {
      .col#{$infix}-#{$i} {
        @extend %grid-column;
      }
    }
    .col#{$infix},
    .col#{$infix}-auto {
      @extend %grid-column;
    }

    @include media-breakpoint-up($breakpoint, $breakpoints) {
      // Provide basic `.col-{bp}` classes for equal-width flexbox columns
      .col#{$infix} {
        flex-basis: 0;
        flex-grow: 1;
        min-width: 0; // See https://github.com/twbs/bootstrap/issues/25410
        max-width: 100%;
      }

      @for $i from 1 through $grid-row-columns {
        .row-cols#{$infix}-#{$i} {
          @include row-cols($i);
        }
      }

      .col#{$infix}-auto {
        @include make-col-auto();
      }

      @for $i from 1 through $columns {
        .col#{$infix}-#{$i} {
          @include make-col($i, $columns);
        }
      }

      // `$columns - 1` because offsetting by the width of an entire row isn't possible
      @for $i from 0 through ($columns - 1) {
        @if not ($infix == "" and $i == 0) { // Avoid emitting useless .offset-0
          .offset#{$infix}-#{$i} {
            @include make-col-offset($i, $columns);
          }
        }
      }
    }
  }
}

// Single container class with breakpoint max-widths
.container {
  @include make-container();
  @include make-container-max-widths();
}

// 100% wide container at all breakpoints
.container-fluid {
  @include make-container();
}

// Responsive containers that are 100% wide until a breakpoint
@each $breakpoint, $container-max-width in $container-max-widths {
  .container-#{$breakpoint} {
    @extend .container-fluid;
  }

  @include media-breakpoint-up($breakpoint, $grid-breakpoints) {
    %responsive-container-#{$breakpoint} {
      max-width: $container-max-width;
    }

    // Extend each breakpoint which is smaller or equal to the current breakpoint
    $extend-breakpoint: true;

    @each $name, $width in $grid-breakpoints {
      @if ($extend-breakpoint) {
        .container#{breakpoint-infix($name, $grid-breakpoints)} {
          @extend %responsive-container-#{$breakpoint};
        }

        // Once the current breakpoint is reached, stop extending
        @if ($breakpoint == $name) {
          $extend-breakpoint: false;
        }
      }
    }
  }
}

.row {
  @include make-row();
}

// Remove the negative margin from default .row, then the horizontal padding from all immediate children columns (to prevent runaway style inheritance).
.no-gutters {
  margin-right: 0;
  margin-left: 0;

  > .col,
  > [class*="col-"] {
    padding-right: 0;
    padding-left: 0;
  }
}

// Common styles for small and large grid columns
@include make-grid-columns();