Add initial docs

docs/input/assets/bootstrap/mixins/_alert.scss

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+@mixin alert-variant($background, $border, $color) {
+  color: $color;
+  @include gradient-bg($background);
+  border-color: $border;
+
+  hr {
+    border-top-color: darken($border, 5%);
+  }
+
+  .alert-link {
+    color: darken($color, 10%);
+  }
+}

docs/input/assets/bootstrap/mixins/_background-variant.scss

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+// stylelint-disable declaration-no-important
+
+// Contextual backgrounds
+
+@mixin bg-variant($parent, $color, $ignore-warning: false) {
+  #{$parent} {
+    background-color: $color !important;
+  }
+  a#{$parent},
+  button#{$parent} {
+    @include hover-focus() {
+      background-color: darken($color, 10%) !important;
+    }
+  }
+  @include deprecate("The `bg-variant` mixin", "v4.4.0", "v5", $ignore-warning);
+}
+
+@mixin bg-gradient-variant($parent, $color) {
+  #{$parent} {
+    background: $color linear-gradient(180deg, $color, darken($color, 3%)) repeat-x !important;
+  }
+}

docs/input/assets/bootstrap/mixins/_badge.scss

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+@mixin badge-variant($bg) {
+  color: color-yiq($bg);
+  background-color: $bg;
+
+  @at-root a#{&} {
+    @include hover-focus() {
+      color: color-yiq($bg);
+      background-color: darken($bg, 10%);
+    }
+
+    &:focus,
+    &.focus {
+      outline: 0;
+      box-shadow: 0 0 0 $badge-focus-width rgba($bg, .5);
+    }
+  }
+}

docs/input/assets/bootstrap/mixins/_border-radius.scss

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+// stylelint-disable property-blacklist
+// Single side border-radius
+
+@mixin border-radius($radius: $border-radius, $fallback-border-radius: false) {
+  @if $enable-rounded {
+    border-radius: $radius;
+  }
+  @else if $fallback-border-radius != false {
+    border-radius: $fallback-border-radius;
+  }
+}
+
+@mixin border-top-radius($radius) {
+  @if $enable-rounded {
+    border-top-left-radius: $radius;
+    border-top-right-radius: $radius;
+  }
+}
+
+@mixin border-right-radius($radius) {
+  @if $enable-rounded {
+    border-top-right-radius: $radius;
+    border-bottom-right-radius: $radius;
+  }
+}
+
+@mixin border-bottom-radius($radius) {
+  @if $enable-rounded {
+    border-bottom-right-radius: $radius;
+    border-bottom-left-radius: $radius;
+  }
+}
+
+@mixin border-left-radius($radius) {
+  @if $enable-rounded {
+    border-top-left-radius: $radius;
+    border-bottom-left-radius: $radius;
+  }
+}
+
+@mixin border-top-left-radius($radius) {
+  @if $enable-rounded {
+    border-top-left-radius: $radius;
+  }
+}
+
+@mixin border-top-right-radius($radius) {
+  @if $enable-rounded {
+    border-top-right-radius: $radius;
+  }
+}
+
+@mixin border-bottom-right-radius($radius) {
+  @if $enable-rounded {
+    border-bottom-right-radius: $radius;
+  }
+}
+
+@mixin border-bottom-left-radius($radius) {
+  @if $enable-rounded {
+    border-bottom-left-radius: $radius;
+  }
+}

docs/input/assets/bootstrap/mixins/_box-shadow.scss

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+@mixin box-shadow($shadow...) {
+  @if $enable-shadows {
+    $result: ();
+
+    @if (length($shadow) == 1) {
+      // We can pass `@include box-shadow(none);`
+      $result: $shadow;
+    } @else {
+      // Filter to avoid invalid properties for example `box-shadow: none, 1px 1px black;`
+      @for $i from 1 through length($shadow) {
+        @if nth($shadow, $i) != "none" {
+          $result: append($result, nth($shadow, $i), "comma");
+        }
+      }
+    }
+    @if (length($result) > 0) {
+      box-shadow: $result;
+    }
+  }
+}

docs/input/assets/bootstrap/mixins/_breakpoints.scss

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+// Breakpoint viewport sizes and media queries.
+//
+// Breakpoints are defined as a map of (name: minimum width), order from small to large:
+//
+//    (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px)
+//
+// The map defined in the `$grid-breakpoints` global variable is used as the `$breakpoints` argument by default.
+
+// Name of the next breakpoint, or null for the last breakpoint.
+//
+//    >> breakpoint-next(sm)
+//    md
+//    >> breakpoint-next(sm, (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px))
+//    md
+//    >> breakpoint-next(sm, $breakpoint-names: (xs sm md lg xl))
+//    md
+@function breakpoint-next($name, $breakpoints: $grid-breakpoints, $breakpoint-names: map-keys($breakpoints)) {
+  $n: index($breakpoint-names, $name);
+  @return if($n != null and $n < length($breakpoint-names), nth($breakpoint-names, $n + 1), null);
+}
+
+// Minimum breakpoint width. Null for the smallest (first) breakpoint.
+//
+//    >> breakpoint-min(sm, (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px))
+//    576px
+@function breakpoint-min($name, $breakpoints: $grid-breakpoints) {
+  $min: map-get($breakpoints, $name);
+  @return if($min != 0, $min, null);
+}
+
+// Maximum breakpoint width. Null for the largest (last) breakpoint.
+// The maximum value is calculated as the minimum of the next one less 0.02px
+// to work around the limitations of `min-` and `max-` prefixes and viewports with fractional widths.
+// See https://www.w3.org/TR/mediaqueries-4/#mq-min-max
+// Uses 0.02px rather than 0.01px to work around a current rounding bug in Safari.
+// See https://bugs.webkit.org/show_bug.cgi?id=178261
+//
+//    >> breakpoint-max(sm, (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px))
+//    767.98px
+@function breakpoint-max($name, $breakpoints: $grid-breakpoints) {
+  $next: breakpoint-next($name, $breakpoints);
+  @return if($next, breakpoint-min($next, $breakpoints) - .02, null);
+}
+
+// Returns a blank string if smallest breakpoint, otherwise returns the name with a dash in front.
+// Useful for making responsive utilities.
+//
+//    >> breakpoint-infix(xs, (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px))
+//    ""  (Returns a blank string)
+//    >> breakpoint-infix(sm, (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px))
+//    "-sm"
+@function breakpoint-infix($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: $min) {
+      @content;
+    }
+  } @else {
+    @content;
+  }
+}
+
+// Media of at most the maximum breakpoint width. No query for the largest breakpoint.
+// Makes the @content apply to the given breakpoint and narrower.
+@mixin media-breakpoint-down($name, $breakpoints: $grid-breakpoints) {
+  $max: breakpoint-max($name, $breakpoints);
+  @if $max {
+    @media (max-width: $max) {
+      @content;
+    }
+  } @else {
+    @content;
+  }
+}
+
+// Media that spans multiple breakpoint widths.
+// Makes the @content apply between the min and max breakpoints
+@mixin media-breakpoint-between($lower, $upper, $breakpoints: $grid-breakpoints) {
+  $min: breakpoint-min($lower, $breakpoints);
+  $max: breakpoint-max($upper, $breakpoints);
+
+  @if $min != null and $max != null {
+    @media (min-width: $min) and (max-width: $max) {
+      @content;
+    }
+  } @else if $max == null {
+    @include media-breakpoint-up($lower, $breakpoints) {
+      @content;
+    }
+  } @else if $min == null {
+    @include media-breakpoint-down($upper, $breakpoints) {
+      @content;
+    }
+  }
+}
+
+// Media between the breakpoint's minimum and maximum widths.
+// No minimum for the smallest breakpoint, and no maximum for the largest one.
+// Makes the @content apply only to the given breakpoint, not viewports any wider or narrower.
+@mixin media-breakpoint-only($name, $breakpoints: $grid-breakpoints) {
+  $min: breakpoint-min($name, $breakpoints);
+  $max: breakpoint-max($name, $breakpoints);
+
+  @if $min != null and $max != null {
+    @media (min-width: $min) and (max-width: $max) {
+      @content;
+    }
+  } @else if $max == null {
+    @include media-breakpoint-up($name, $breakpoints) {
+      @content;
+    }
+  } @else if $min == null {
+    @include media-breakpoint-down($name, $breakpoints) {
+      @content;
+    }
+  }
+}

docs/input/assets/bootstrap/mixins/_buttons.scss

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+// Button variants
+//
+// Easily pump out default styles, as well as :hover, :focus, :active,
+// and disabled options for all buttons
+
+@mixin button-variant($background, $border, $hover-background: darken($background, 7.5%), $hover-border: darken($border, 10%), $active-background: darken($background, 10%), $active-border: darken($border, 12.5%)) {
+  color: color-yiq($background);
+  @include gradient-bg($background);
+  border-color: $border;
+  @include box-shadow($btn-box-shadow);
+
+  @include hover() {
+    color: color-yiq($hover-background);
+    @include gradient-bg($hover-background);
+    border-color: $hover-border;
+  }
+
+  &:focus,
+  &.focus {
+    color: color-yiq($hover-background);
+    @include gradient-bg($hover-background);
+    border-color: $hover-border;
+    // Avoid using mixin so we can pass custom focus shadow properly
+    @if $enable-shadows {
+      box-shadow: $btn-box-shadow, 0 0 0 $btn-focus-width rgba(mix(color-yiq($background), $border, 15%), .5);
+    } @else {
+      box-shadow: 0 0 0 $btn-focus-width rgba(mix(color-yiq($background), $border, 15%), .5);
+    }
+  }
+
+  // Disabled comes first so active can properly restyle
+  &.disabled,
+  &:disabled {
+    color: color-yiq($background);
+    background-color: $background;
+    border-color: $border;
+    // Remove CSS gradients if they're enabled
+    @if $enable-gradients {
+      background-image: none;
+    }
+  }
+
+  &:not(:disabled):not(.disabled):active,
+  &:not(:disabled):not(.disabled).active,
+  .show > &.dropdown-toggle {
+    color: color-yiq($active-background);
+    background-color: $active-background;
+    @if $enable-gradients {
+      background-image: none; // Remove the gradient for the pressed/active state
+    }
+    border-color: $active-border;
+
+    &:focus {
+      // Avoid using mixin so we can pass custom focus shadow properly
+      @if $enable-shadows and $btn-active-box-shadow != none {
+        box-shadow: $btn-active-box-shadow, 0 0 0 $btn-focus-width rgba(mix(color-yiq($background), $border, 15%), .5);
+      } @else {
+        box-shadow: 0 0 0 $btn-focus-width rgba(mix(color-yiq($background), $border, 15%), .5);
+      }
+    }
+  }
+}
+
+@mixin button-outline-variant($color, $color-hover: color-yiq($color), $active-background: $color, $active-border: $color) {
+  color: $color;
+  border-color: $color;
+
+  @include hover() {
+    color: $color-hover;
+    background-color: $active-background;
+    border-color: $active-border;
+  }
+
+  &:focus,
+  &.focus {
+    box-shadow: 0 0 0 $btn-focus-width rgba($color, .5);
+  }
+
+  &.disabled,
+  &:disabled {
+    color: $color;
+    background-color: transparent;
+  }
+
+  &:not(:disabled):not(.disabled):active,
+  &:not(:disabled):not(.disabled).active,
+  .show > &.dropdown-toggle {
+    color: color-yiq($active-background);
+    background-color: $active-background;
+    border-color: $active-border;
+
+    &:focus {
+      // Avoid using mixin so we can pass custom focus shadow properly
+      @if $enable-shadows and $btn-active-box-shadow != none {
+        box-shadow: $btn-active-box-shadow, 0 0 0 $btn-focus-width rgba($color, .5);
+      } @else {
+        box-shadow: 0 0 0 $btn-focus-width rgba($color, .5);
+      }
+    }
+  }
+}
+
+// Button sizes
+@mixin button-size($padding-y, $padding-x, $font-size, $line-height, $border-radius) {
+  padding: $padding-y $padding-x;
+  @include font-size($font-size);
+  line-height: $line-height;
+  // Manually declare to provide an override to the browser default
+  @include border-radius($border-radius, 0);
+}

docs/input/assets/bootstrap/mixins/_caret.scss

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+@mixin caret-down() {
+  border-top: $caret-width solid;
+  border-right: $caret-width solid transparent;
+  border-bottom: 0;
+  border-left: $caret-width solid transparent;
+}
+
+@mixin caret-up() {
+  border-top: 0;
+  border-right: $caret-width solid transparent;
+  border-bottom: $caret-width solid;
+  border-left: $caret-width solid transparent;
+}
+
+@mixin caret-right() {
+  border-top: $caret-width solid transparent;
+  border-right: 0;
+  border-bottom: $caret-width solid transparent;
+  border-left: $caret-width solid;
+}
+
+@mixin caret-left() {
+  border-top: $caret-width solid transparent;
+  border-right: $caret-width solid;
+  border-bottom: $caret-width solid transparent;
+}
+
+@mixin caret($direction: down) {
+  @if $enable-caret {
+    &::after {
+      display: inline-block;
+      margin-left: $caret-spacing;
+      vertical-align: $caret-vertical-align;
+      content: "";
+      @if $direction == down {
+        @include caret-down();
+      } @else if $direction == up {
+        @include caret-up();
+      } @else if $direction == right {
+        @include caret-right();
+      }
+    }
+
+    @if $direction == left {
+      &::after {
+        display: none;
+      }
+
+      &::before {
+        display: inline-block;
+        margin-right: $caret-spacing;
+        vertical-align: $caret-vertical-align;
+        content: "";
+        @include caret-left();
+      }
+    }
+
+    &:empty::after {
+      margin-left: 0;
+    }
+  }
+}

docs/input/assets/bootstrap/mixins/_clearfix.scss

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+@mixin clearfix() {
+  &::after {
+    display: block;
+    clear: both;
+    content: "";
+  }
+}

docs/input/assets/bootstrap/mixins/_deprecate.scss

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+// Deprecate mixin
+//
+// This mixin can be used to deprecate mixins or functions.
+// `$enable-deprecation-messages` is a global variable, `$ignore-warning` is a variable that can be passed to
+// some deprecated mixins to suppress the warning (for example if the mixin is still be used in the current version of Bootstrap)
+@mixin deprecate($name, $deprecate-version, $remove-version, $ignore-warning: false) {
+  @if ($enable-deprecation-messages != false and $ignore-warning != true) {
+    @warn "#{$name} has been deprecated as of #{$deprecate-version}. It will be removed entirely in #{$remove-version}.";
+  }
+}

docs/input/assets/bootstrap/mixins/_float.scss

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+// stylelint-disable declaration-no-important
+
+@mixin float-left() {
+  float: left !important;
+  @include deprecate("The `float-left` mixin", "v4.3.0", "v5");
+}
+@mixin float-right() {
+  float: right !important;
+  @include deprecate("The `float-right` mixin", "v4.3.0", "v5");
+}
+@mixin float-none() {
+  float: none !important;
+  @include deprecate("The `float-none` mixin", "v4.3.0", "v5");
+}

docs/input/assets/bootstrap/mixins/_forms.scss

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+// Form control focus state
+//
+// Generate a customized focus state and for any input with the specified color,
+// which defaults to the `$input-focus-border-color` variable.
+//
+// We highly encourage you to not customize the default value, but instead use
+// this to tweak colors on an as-needed basis. This aesthetic change is based on
+// WebKit's default styles, but applicable to a wider range of browsers. Its
+// usability and accessibility should be taken into account with any change.
+//
+// Example usage: change the default blue border and shadow to white for better
+// contrast against a dark gray background.
+@mixin form-control-focus($ignore-warning: false) {
+  &:focus {
+    color: $input-focus-color;
+    background-color: $input-focus-bg;
+    border-color: $input-focus-border-color;
+    outline: 0;
+    // Avoid using mixin so we can pass custom focus shadow properly
+    @if $enable-shadows {
+      box-shadow: $input-box-shadow, $input-focus-box-shadow;
+    } @else {
+      box-shadow: $input-focus-box-shadow;
+    }
+  }
+  @include deprecate("The `form-control-focus()` mixin", "v4.4.0", "v5", $ignore-warning);
+}
+
+// This mixin uses an `if()` technique to be compatible with Dart Sass
+// See https://github.com/sass/sass/issues/1873#issuecomment-152293725 for more details
+@mixin form-validation-state-selector($state) {
+  @if ($state == "valid" or $state == "invalid") {
+    .was-validated #{if(&, "&", "")}:#{$state},
+    #{if(&, "&", "")}.is-#{$state} {
+      @content;
+    }
+  } @else {
+    #{if(&, "&", "")}.is-#{$state} {
+      @content;
+    }
+  }
+}
+
+@mixin form-validation-state($state, $color, $icon) {
+  .#{$state}-feedback {
+    display: none;
+    width: 100%;
+    margin-top: $form-feedback-margin-top;
+    @include font-size($form-feedback-font-size);
+    color: $color;
+  }
+
+  .#{$state}-tooltip {
+    position: absolute;
+    top: 100%;
+    z-index: 5;
+    display: none;
+    max-width: 100%; // Contain to parent when possible
+    padding: $form-feedback-tooltip-padding-y $form-feedback-tooltip-padding-x;
+    margin-top: .1rem;
+    @include font-size($form-feedback-tooltip-font-size);
+    line-height: $form-feedback-tooltip-line-height;
+    color: color-yiq($color);
+    background-color: rgba($color, $form-feedback-tooltip-opacity);
+    @include border-radius($form-feedback-tooltip-border-radius);
+  }
+
+  @include form-validation-state-selector($state) {
+    ~ .#{$state}-feedback,
+    ~ .#{$state}-tooltip {
+      display: block;
+    }
+  }
+
+  .form-control {
+    @include form-validation-state-selector($state) {
+      border-color: $color;
+
+      @if $enable-validation-icons {
+        padding-right: $input-height-inner;
+        background-image: escape-svg($icon);
+        background-repeat: no-repeat;
+        background-position: right $input-height-inner-quarter center;
+        background-size: $input-height-inner-half $input-height-inner-half;
+      }
+
+      &:focus {
+        border-color: $color;
+        box-shadow: 0 0 0 $input-focus-width rgba($color, .25);
+      }
+    }
+  }
+
+  // stylelint-disable-next-line selector-no-qualifying-type
+  textarea.form-control {
+    @include form-validation-state-selector($state) {
+      @if $enable-validation-icons {
+        padding-right: $input-height-inner;
+        background-position: top $input-height-inner-quarter right $input-height-inner-quarter;
+      }
+    }
+  }
+
+  .custom-select {
+    @include form-validation-state-selector($state) {
+      border-color: $color;
+
+      @if $enable-validation-icons {
+        padding-right: $custom-select-feedback-icon-padding-right;
+        background: $custom-select-background, escape-svg($icon) $custom-select-bg no-repeat $custom-select-feedback-icon-position / $custom-select-feedback-icon-size;
+      }
+
+      &:focus {
+        border-color: $color;
+        box-shadow: 0 0 0 $input-focus-width rgba($color, .25);
+      }
+    }
+  }
+
+  .form-check-input {
+    @include form-validation-state-selector($state) {
+      ~ .form-check-label {
+        color: $color;
+      }
+
+      ~ .#{$state}-feedback,
+      ~ .#{$state}-tooltip {
+        display: block;
+      }
+    }
+  }
+
+  .custom-control-input {
+    @include form-validation-state-selector($state) {
+      ~ .custom-control-label {
+        color: $color;
+
+        &::before {
+          border-color: $color;
+        }
+      }
+
+      &:checked {
+        ~ .custom-control-label::before {
+          border-color: lighten($color, 10%);
+          @include gradient-bg(lighten($color, 10%));
+        }
+      }
+
+      &:focus {
+        ~ .custom-control-label::before {
+          box-shadow: 0 0 0 $input-focus-width rgba($color, .25);
+        }
+
+        &:not(:checked) ~ .custom-control-label::before {
+          border-color: $color;
+        }
+      }
+    }
+  }
+
+  // custom file
+  .custom-file-input {
+    @include form-validation-state-selector($state) {
+      ~ .custom-file-label {
+        border-color: $color;
+      }
+
+      &:focus {
+        ~ .custom-file-label {
+          border-color: $color;
+          box-shadow: 0 0 0 $input-focus-width rgba($color, .25);
+        }
+      }
+    }
+  }
+}

docs/input/assets/bootstrap/mixins/_gradients.scss

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+// Gradients
+
+@mixin gradient-bg($color) {
+  @if $enable-gradients {
+    background: $color linear-gradient(180deg, mix($body-bg, $color, 15%), $color) repeat-x;
+  } @else {
+    background-color: $color;
+  }
+}
+
+// Horizontal gradient, from left to right
+//
+// Creates two color stops, start and end, by specifying a color and position for each color stop.
+@mixin gradient-x($start-color: $gray-700, $end-color: $gray-800, $start-percent: 0%, $end-percent: 100%) {
+  background-image: linear-gradient(to right, $start-color $start-percent, $end-color $end-percent);
+  background-repeat: repeat-x;
+}
+
+// Vertical gradient, from top to bottom
+//
+// Creates two color stops, start and end, by specifying a color and position for each color stop.
+@mixin gradient-y($start-color: $gray-700, $end-color: $gray-800, $start-percent: 0%, $end-percent: 100%) {
+  background-image: linear-gradient(to bottom, $start-color $start-percent, $end-color $end-percent);
+  background-repeat: repeat-x;
+}
+
+@mixin gradient-directional($start-color: $gray-700, $end-color: $gray-800, $deg: 45deg) {
+  background-image: linear-gradient($deg, $start-color, $end-color);
+  background-repeat: repeat-x;
+}
+@mixin gradient-x-three-colors($start-color: $blue, $mid-color: $purple, $color-stop: 50%, $end-color: $red) {
+  background-image: linear-gradient(to right, $start-color, $mid-color $color-stop, $end-color);
+  background-repeat: no-repeat;
+}
+@mixin gradient-y-three-colors($start-color: $blue, $mid-color: $purple, $color-stop: 50%, $end-color: $red) {
+  background-image: linear-gradient($start-color, $mid-color $color-stop, $end-color);
+  background-repeat: no-repeat;
+}
+@mixin gradient-radial($inner-color: $gray-700, $outer-color: $gray-800) {
+  background-image: radial-gradient(circle, $inner-color, $outer-color);
+  background-repeat: no-repeat;
+}
+@mixin gradient-striped($color: rgba($white, .15), $angle: 45deg) {
+  background-image: linear-gradient($angle, $color 25%, transparent 25%, transparent 50%, $color 50%, $color 75%, transparent 75%, transparent);
+}

docs/input/assets/bootstrap/mixins/_grid-framework.scss

@@ -0,0 +1,71 @@
+// Framework grid generation
+//
+// 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;
+        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, $columns);
+        }
+      }
+
+      .order#{$infix}-first { order: -1; }
+
+      .order#{$infix}-last { order: $columns + 1; }
+
+      @for $i from 0 through $columns {
+        .order#{$infix}-#{$i} { order: $i; }
+      }
+
+      // `$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);
+          }
+        }
+      }
+    }
+  }
+}

docs/input/assets/bootstrap/mixins/_grid.scss

@@ -0,0 +1,69 @@
+/// Grid system
+//
+// Generate semantic grid columns with these mixins.
+
+@mixin make-container($gutter: $grid-gutter-width) {
+  width: 100%;
+  padding-right: $gutter / 2;
+  padding-left: $gutter / 2;
+  margin-right: auto;
+  margin-left: auto;
+}
+
+
+// For each breakpoint, define the maximum width of the container in a media query
+@mixin make-container-max-widths($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: -$gutter / 2;
+}
+
+@mixin make-col-ready($gutter: $grid-gutter-width) {
+  position: relative;
+  // Prevent columns from becoming too narrow when at smaller grid tiers by
+  // always setting `width: 100%;`. This works because we use `flex` values
+  // later on to override this initial width.
+  width: 100%;
+  padding-right: $gutter / 2;
+  padding-left: $gutter / 2;
+}
+
+@mixin make-col($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 / $columns);
+}
+
+@mixin make-col-auto() {
+  flex: 0 0 auto;
+  width: auto;
+  max-width: 100%; // Reset earlier grid tiers
+}
+
+@mixin make-col-offset($size, $columns: $grid-columns) {
+  $num: $size / $columns;
+  margin-left: if($num == 0, 0, percentage($num));
+}
+
+// Row columns
+//
+// Specify on a parent element(e.g., .row) to force immediate children into NN
+// numberof columns. Supports wrapping to new lines, but does not do a Masonry
+// style grid.
+@mixin row-cols($count) {
+  & > * {
+    flex: 0 0 100% / $count;
+    max-width: 100% / $count;
+  }
+}

docs/input/assets/bootstrap/mixins/_hover.scss

@@ -0,0 +1,37 @@
+// Hover mixin and `$enable-hover-media-query` are deprecated.
+//
+// Originally added during our alphas and maintained during betas, this mixin was
+// designed to prevent `:hover` stickiness on iOS-an issue where hover styles
+// would persist after initial touch.
+//
+// For backward compatibility, we've kept these mixins and updated them to
+// always return their regular pseudo-classes instead of a shimmed media query.
+//
+// Issue: https://github.com/twbs/bootstrap/issues/25195
+
+@mixin hover() {
+  &:hover { @content; }
+}
+
+@mixin hover-focus() {
+  &:hover,
+  &:focus {
+    @content;
+  }
+}
+
+@mixin plain-hover-focus() {
+  &,
+  &:hover,
+  &:focus {
+    @content;
+  }
+}
+
+@mixin hover-focus-active() {
+  &:hover,
+  &:focus,
+  &:active {
+    @content;
+  }
+}

docs/input/assets/bootstrap/mixins/_image.scss

@@ -0,0 +1,36 @@
+// Image Mixins
+// - Responsive image
+// - Retina image
+
+
+// Responsive image
+//
+// Keep images from scaling beyond the width of their parents.
+
+@mixin img-fluid() {
+  // Part 1: Set a maximum relative to the parent
+  max-width: 100%;
+  // Part 2: Override the height to auto, otherwise images will be stretched
+  // when setting a width and height attribute on the img element.
+  height: auto;
+}
+
+
+// Retina image
+//
+// Short retina mixin for setting background-image and -size.
+
+@mixin img-retina($file-1x, $file-2x, $width-1x, $height-1x) {
+  background-image: url($file-1x);
+
+  // Autoprefixer takes care of adding -webkit-min-device-pixel-ratio and -o-min-device-pixel-ratio,
+  // but doesn't convert dppx=>dpi.
+  // There's no such thing as unprefixed min-device-pixel-ratio since it's nonstandard.
+  // Compatibility info: https://caniuse.com/#feat=css-media-resolution
+  @media only screen and (min-resolution: 192dpi), // IE9-11 don't support dppx
+    only screen and (min-resolution: 2dppx) { // Standardized
+    background-image: url($file-2x);
+    background-size: $width-1x $height-1x;
+  }
+  @include deprecate("`img-retina()`", "v4.3.0", "v5");
+}

docs/input/assets/bootstrap/mixins/_list-group.scss

@@ -0,0 +1,21 @@
+// List Groups
+
+@mixin list-group-item-variant($state, $background, $color) {
+  .list-group-item-#{$state} {
+    color: $color;
+    background-color: $background;
+
+    &.list-group-item-action {
+      @include hover-focus() {
+        color: $color;
+        background-color: darken($background, 5%);
+      }
+
+      &.active {
+        color: $white;
+        background-color: $color;
+        border-color: $color;
+      }
+    }
+  }
+}

docs/input/assets/bootstrap/mixins/_lists.scss

@@ -0,0 +1,7 @@
+// Lists
+
+// Unstyled keeps list items block level, just removes default browser padding and list-style
+@mixin list-unstyled() {
+  padding-left: 0;
+  list-style: none;
+}

docs/input/assets/bootstrap/mixins/_nav-divider.scss

@@ -0,0 +1,11 @@
+// Horizontal dividers
+//
+// Dividers (basically an hr) within dropdowns and nav lists
+
+@mixin nav-divider($color: $nav-divider-color, $margin-y: $nav-divider-margin-y, $ignore-warning: false) {
+  height: 0;
+  margin: $margin-y 0;
+  overflow: hidden;
+  border-top: 1px solid $color;
+  @include deprecate("The `nav-divider()` mixin", "v4.4.0", "v5", $ignore-warning);
+}

docs/input/assets/bootstrap/mixins/_pagination.scss

@@ -0,0 +1,22 @@
+// Pagination
+
+@mixin pagination-size($padding-y, $padding-x, $font-size, $line-height, $border-radius) {
+  .page-link {
+    padding: $padding-y $padding-x;
+    @include font-size($font-size);
+    line-height: $line-height;
+  }
+
+  .page-item {
+    &:first-child {
+      .page-link {
+        @include border-left-radius($border-radius);
+      }
+    }
+    &:last-child {
+      .page-link {
+        @include border-right-radius($border-radius);
+      }
+    }
+  }
+}

docs/input/assets/bootstrap/mixins/_reset-text.scss

@@ -0,0 +1,17 @@
+@mixin reset-text() {
+  font-family: $font-family-base;
+  // We deliberately do NOT reset font-size or word-wrap.
+  font-style: normal;
+  font-weight: $font-weight-normal;
+  line-height: $line-height-base;
+  text-align: left; // Fallback for where `start` is not supported
+  text-align: start;
+  text-decoration: none;
+  text-shadow: none;
+  text-transform: none;
+  letter-spacing: normal;
+  word-break: normal;
+  word-spacing: normal;
+  white-space: normal;
+  line-break: auto;
+}

docs/input/assets/bootstrap/mixins/_resize.scss

@@ -0,0 +1,6 @@
+// Resize anything
+
+@mixin resizable($direction) {
+  overflow: auto; // Per CSS3 UI, `resize` only applies when `overflow` isn't `visible`
+  resize: $direction; // Options: horizontal, vertical, both
+}

docs/input/assets/bootstrap/mixins/_screen-reader.scss

@@ -0,0 +1,34 @@
+// Only display content to screen readers
+//
+// See: https://a11yproject.com/posts/how-to-hide-content/
+// See: https://hugogiraudel.com/2016/10/13/css-hide-and-seek/
+
+@mixin sr-only() {
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  padding: 0;
+  margin: -1px; // Fix for https://github.com/twbs/bootstrap/issues/25686
+  overflow: hidden;
+  clip: rect(0, 0, 0, 0);
+  white-space: nowrap;
+  border: 0;
+}
+
+// Use in conjunction with .sr-only to only display content when it's focused.
+//
+// Useful for "Skip to main content" links; see https://www.w3.org/TR/2013/NOTE-WCAG20-TECHS-20130905/G1
+//
+// Credit: HTML5 Boilerplate
+
+@mixin sr-only-focusable() {
+  &:active,
+  &:focus {
+    position: static;
+    width: auto;
+    height: auto;
+    overflow: visible;
+    clip: auto;
+    white-space: normal;
+  }
+}

docs/input/assets/bootstrap/mixins/_size.scss

@@ -0,0 +1,7 @@
+// Sizing shortcuts
+
+@mixin size($width, $height: $width) {
+  width: $width;
+  height: $height;
+  @include deprecate("`size()`", "v4.3.0", "v5");
+}

docs/input/assets/bootstrap/mixins/_table-row.scss

@@ -0,0 +1,39 @@
+// Tables
+
+@mixin table-row-variant($state, $background, $border: null) {
+  // Exact selectors below required to override `.table-striped` and prevent
+  // inheritance to nested tables.
+  .table-#{$state} {
+    &,
+    > th,
+    > td {
+      background-color: $background;
+    }
+
+    @if $border != null {
+      th,
+      td,
+      thead th,
+      tbody + tbody {
+        border-color: $border;
+      }
+    }
+  }
+
+  // Hover states for `.table-hover`
+  // Note: this is not available for cells or rows within `thead` or `tfoot`.
+  .table-hover {
+    $hover-background: darken($background, 5%);
+
+    .table-#{$state} {
+      @include hover() {
+        background-color: $hover-background;
+
+        > td,
+        > th {
+          background-color: $hover-background;
+        }
+      }
+    }
+  }
+}

docs/input/assets/bootstrap/mixins/_text-emphasis.scss

@@ -0,0 +1,17 @@
+// stylelint-disable declaration-no-important
+
+// Typography
+
+@mixin text-emphasis-variant($parent, $color, $ignore-warning: false) {
+  #{$parent} {
+    color: $color !important;
+  }
+  @if $emphasized-link-hover-darken-percentage != 0 {
+    a#{$parent} {
+      @include hover-focus() {
+        color: darken($color, $emphasized-link-hover-darken-percentage) !important;
+      }
+    }
+  }
+  @include deprecate("`text-emphasis-variant()`", "v4.4.0", "v5", $ignore-warning);
+}

docs/input/assets/bootstrap/mixins/_text-hide.scss

@@ -0,0 +1,11 @@
+// CSS image replacement
+@mixin text-hide($ignore-warning: false) {
+  // stylelint-disable-next-line font-family-no-missing-generic-family-keyword
+  font: 0/0 a;
+  color: transparent;
+  text-shadow: none;
+  background-color: transparent;
+  border: 0;
+
+  @include deprecate("`text-hide()`", "v4.1.0", "v5", $ignore-warning);
+}

docs/input/assets/bootstrap/mixins/_text-truncate.scss

@@ -0,0 +1,8 @@
+// Text truncate
+// Requires inline-block or block for proper styling
+
+@mixin text-truncate() {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}

docs/input/assets/bootstrap/mixins/_transition.scss

@@ -0,0 +1,16 @@
+// stylelint-disable property-blacklist
+@mixin transition($transition...) {
+  @if $enable-transitions {
+    @if length($transition) == 0 {
+      transition: $transition-base;
+    } @else {
+      transition: $transition;
+    }
+  }
+
+  @if $enable-prefers-reduced-motion-media-query {
+    @media (prefers-reduced-motion: reduce) {
+      transition: none;
+    }
+  }
+}

docs/input/assets/bootstrap/mixins/_visibility.scss

@@ -0,0 +1,8 @@
+// stylelint-disable declaration-no-important
+
+// Visibility
+
+@mixin invisible($visibility) {
+  visibility: $visibility !important;
+  @include deprecate("`invisible()`", "v4.3.0", "v5");
+}