Responsive Border Utilities for Bootstrap 4.1

_border-utilities.scss

// stylelint-disable declaration-no-important

//
// Border
//

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

    .border#{$infix}-top {      border-top: $border-width solid $border-color !important; }
    .border#{$infix}-right {    border-right: $border-width solid $border-color !important; }
    .border#{$infix}-bottom {   border-bottom: $border-width solid $border-color !important; }
    .border#{$infix}-left {     border-left: $border-width solid $border-color !important; }

    .border#{$infix}-top-0 {    border-top: 0 !important; }
    .border#{$infix}-right-0 {  border-right: 0 !important; }
    .border#{$infix}-bottom-0 { border-bottom: 0 !important; }
    .border#{$infix}-left-0 {   border-left: 0 !important; }

    .border#{$infix}-x {
      border-left: $border-width solid $border-color !important;
      border-right: $border-width solid $border-color !important;
    }

    .border#{$infix}-y {
      border-top: $border-width solid $border-color !important;
      border-bottom: $border-width solid $border-color !important;
    }
  }
}

@each $color, $value in $theme-colors {
  .border-#{$color} {
    border-color: $value !important;
  }
}

.border-white {
  border-color: $white !important;
}

//
// Border-radius
//

.rounded {
  border-radius: $border-radius !important;
}
.rounded-top {
  border-top-left-radius: $border-radius !important;
  border-top-right-radius: $border-radius !important;
}
.rounded-right {
  border-top-right-radius: $border-radius !important;
  border-bottom-right-radius: $border-radius !important;
}
.rounded-bottom {
  border-bottom-right-radius: $border-radius !important;
  border-bottom-left-radius: $border-radius !important;
}
.rounded-left {
  border-top-left-radius: $border-radius !important;
  border-bottom-left-radius: $border-radius !important;
}

.rounded-circle {
  border-radius: 50% !important;
}

.rounded-0 {
  border-radius: 0 !important;
}