सीमाएँ

<span class="border"></span>
<span class="border-top"></span>
<span class="border-end"></span>
<span class="border-bottom"></span>
<span class="border-start"></span>

<span class="border-0"></span>
<span class="border-top-0"></span>
<span class="border-end-0"></span>
<span class="border-bottom-0"></span>
<span class="border-start-0"></span>

<span class="border border-primary"></span>
<span class="border border-secondary"></span>
<span class="border border-success"></span>
<span class="border border-danger"></span>
<span class="border border-warning"></span>
<span class="border border-info"></span>
<span class="border border-light"></span>
<span class="border border-dark"></span>
<span class="border border-white"></span>

<span class="border border-1"></span>
<span class="border border-2"></span>
<span class="border border-3"></span>
<span class="border border-4"></span>
<span class="border border-5"></span>

<img src="..." class="rounded" alt="...">
<img src="..." class="rounded-top" alt="...">
<img src="..." class="rounded-end" alt="...">
<img src="..." class="rounded-bottom" alt="...">
<img src="..." class="rounded-start" alt="...">
<img src="..." class="rounded-circle" alt="...">
<img src="..." class="rounded-pill" alt="...">

<img src="..." class="rounded-0" alt="...">
<img src="..." class="rounded-1" alt="...">
<img src="..." class="rounded-2" alt="...">
<img src="..." class="rounded-3" alt="...">

$border-width:                1px;
$border-widths: (
  1: 1px,
  2: 2px,
  3: 3px,
  4: 4px,
  5: 5px
);

$border-color:                $gray-300;

$border-radius:               .25rem;
$border-radius-sm:            .2rem;
$border-radius-lg:            .3rem;
$border-radius-pill:          50rem;

@mixin border-radius($radius: $border-radius, $fallback-border-radius: false) {
  @if $enable-rounded {
    border-radius: valid-radius($radius);
  }
  @else if $fallback-border-radius != false {
    border-radius: $fallback-border-radius;
  }
}

@mixin border-top-radius($radius: $border-radius) {
  @if $enable-rounded {
    border-top-left-radius: valid-radius($radius);
    border-top-right-radius: valid-radius($radius);
  }
}

@mixin border-end-radius($radius: $border-radius) {
  @if $enable-rounded {
    border-top-right-radius: valid-radius($radius);
    border-bottom-right-radius: valid-radius($radius);
  }
}

@mixin border-bottom-radius($radius: $border-radius) {
  @if $enable-rounded {
    border-bottom-right-radius: valid-radius($radius);
    border-bottom-left-radius: valid-radius($radius);
  }
}

@mixin border-start-radius($radius: $border-radius) {
  @if $enable-rounded {
    border-top-left-radius: valid-radius($radius);
    border-bottom-left-radius: valid-radius($radius);
  }
}

@mixin border-top-start-radius($radius: $border-radius) {
  @if $enable-rounded {
    border-top-left-radius: valid-radius($radius);
  }
}

@mixin border-top-end-radius($radius: $border-radius) {
  @if $enable-rounded {
    border-top-right-radius: valid-radius($radius);
  }
}

@mixin border-bottom-end-radius($radius: $border-radius) {
  @if $enable-rounded {
    border-bottom-right-radius: valid-radius($radius);
  }
}

@mixin border-bottom-start-radius($radius: $border-radius) {
  @if $enable-rounded {
    border-bottom-left-radius: valid-radius($radius);
  }
}

    "border": (
      property: border,
      values: (
        null: $border-width solid $border-color,
        0: 0,
      )
    ),
    "border-top": (
      property: border-top,
      values: (
        null: $border-width solid $border-color,
        0: 0,
      )
    ),
    "border-end": (
      property: border-right,
      class: border-end,
      values: (
        null: $border-width solid $border-color,
        0: 0,
      )
    ),
    "border-bottom": (
      property: border-bottom,
      values: (
        null: $border-width solid $border-color,
        0: 0,
      )
    ),
    "border-start": (
      property: border-left,
      class: border-start,
      values: (
        null: $border-width solid $border-color,
        0: 0,
      )
    ),
    "border-color": (
      property: border-color,
      class: border,
      values: map-merge($theme-colors, ("white": $white))
    ),
    "border-width": (
      property: border-width,
      class: border,
      values: $border-widths
    ),
    

    "rounded": (
      property: border-radius,
      class: rounded,
      values: (
        null: $border-radius,
        0: 0,
        1: $border-radius-sm,
        2: $border-radius,
        3: $border-radius-lg,
        circle: 50%,
        pill: $border-radius-pill
      )
    ),
    "rounded-top": (
      property: border-top-left-radius border-top-right-radius,
      class: rounded-top,
      values: (null: $border-radius)
    ),
    "rounded-end": (
      property: border-top-right-radius border-bottom-right-radius,
      class: rounded-end,
      values: (null: $border-radius)
    ),
    "rounded-bottom": (
      property: border-bottom-right-radius border-bottom-left-radius,
      class: rounded-bottom,
      values: (null: $border-radius)
    ),
    "rounded-start": (
      property: border-bottom-left-radius border-top-left-radius,
      class: rounded-start,
      values: (null: $border-radius)
    ),