tabler/scss/utils/_border.scss

// stylelint-disable declaration-no-important
$border-sizing: () !default;
$border-sizing: map-merge(
  (
    2: 2,
    4: 4
  ),
  $border-sizing
) !default;

@each $size, $value in $border-sizing {

  .border-#{$size} {
    border-width: $border-width * $value !important;
  }

  .border-top-#{$size} {
    border-top-style: solid;
    border-top-width: $border-width * $value !important;
  }

  .border-right-#{$size} {
    border-right-style: solid;
    border-right-width: $border-width * $value !important;
  }

  .border-bottom-#{$size} {
    border-bottom-style: solid;
    border-bottom-width: $border-width * $value !important;
  }

  .border-left-#{$size} {
    border-left-style: solid;
    border-left-width: $border-width * $value !important;
  }
}

.border-dashed {
  border-style: dashed !important;
}

.border-transparent {
  border-color: transparent !important;
}