bootstrap/scss/_offcanvas.scss

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

  .offcanvas#{$infix} {
    @include media-breakpoint-down($next) {
      position: fixed;
      bottom: 0;
      z-index: $zindex-offcanvas;
      display: flex;
      flex-direction: column;
      max-width: 100%;
      color: $offcanvas-color;
      visibility: hidden;
      background-color: $offcanvas-bg-color;
      background-clip: padding-box;
      outline: 0;
      @include box-shadow($offcanvas-box-shadow);
      @include transition(transform $offcanvas-transition-duration ease-in-out);

      &.showing,
      &.show:not(.hiding) {
        transform: none;
      }

      &.showing,
      &.hiding,
      &.show {
        visibility: visible;
      }

      &.offcanvas-start {
        top: 0;
        left: 0;
        width: $offcanvas-horizontal-width;
        border-right: $offcanvas-border-width solid $offcanvas-border-color;
        transform: translateX(-100%);
      }

      &.offcanvas-end {
        top: 0;
        right: 0;
        width: $offcanvas-horizontal-width;
        border-left: $offcanvas-border-width solid $offcanvas-border-color;
        transform: translateX(100%);
      }

      &.offcanvas-top {
        top: 0;
        right: 0;
        left: 0;
        height: $offcanvas-vertical-height;
        max-height: 100%;
        border-bottom: $offcanvas-border-width solid $offcanvas-border-color;
        transform: translateY(-100%);
      }

      &.offcanvas-bottom {
        right: 0;
        left: 0;
        height: $offcanvas-vertical-height;
        max-height: 100%;
        border-top: $offcanvas-border-width solid $offcanvas-border-color;
        transform: translateY(100%);
      }
    }

    @if not ($infix == "") {
      @include media-breakpoint-up($next) {
        height: auto;
        background-color: transparent !important; // stylelint-disable-line declaration-no-important
        border: 0;

        .offcanvas-header {
          display: none;
        }

        .offcanvas-body {
          display: flex;
          flex-grow: 0;
          padding: 0;
          overflow-y: visible;
          // Reset `background-color` in case `.bg-*` classes are used in offcanvas
          background-color: transparent !important; // stylelint-disable-line declaration-no-important
        }
      }
    }
  }
}


// .offcanvas {
//   position: fixed;
//   bottom: 0;
//   z-index: $zindex-offcanvas;
//   display: flex;
//   flex-direction: column;
//   max-width: 100%;
//   color: $offcanvas-color;
//   visibility: hidden;
//   background-color: $offcanvas-bg-color;
//   background-clip: padding-box;
//   outline: 0;
//   @include box-shadow($offcanvas-box-shadow);
//   @include transition(transform $offcanvas-transition-duration ease-in-out);

//   &.showing,
//   &.show:not(.hiding) {
//     transform: none;
//   }

//   &.showing,
//   &.hiding,
//   &.show {
//     visibility: visible;
//   }
// }

.offcanvas-backdrop {
  @include overlay-backdrop($zindex-offcanvas-backdrop, $offcanvas-backdrop-bg, $offcanvas-backdrop-opacity);
}

.offcanvas-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: $offcanvas-padding-y $offcanvas-padding-x;

  .btn-close {
    padding: ($offcanvas-padding-y * .5) ($offcanvas-padding-x * .5);
    margin-top: $offcanvas-padding-y * -.5;
    margin-right: $offcanvas-padding-x * -.5;
    margin-bottom: $offcanvas-padding-y * -.5;
  }
}

.offcanvas-title {
  margin-bottom: 0;
  line-height: $offcanvas-title-line-height;
}

.offcanvas-body {
  flex-grow: 1;
  padding: $offcanvas-padding-y $offcanvas-padding-x;
  overflow-y: auto;
}

// .offcanvas-start {
//   top: 0;
//   left: 0;
//   width: $offcanvas-horizontal-width;
//   border-right: $offcanvas-border-width solid $offcanvas-border-color;
//   transform: translateX(-100%);
// }

// .offcanvas-end {
//   top: 0;
//   right: 0;
//   width: $offcanvas-horizontal-width;
//   border-left: $offcanvas-border-width solid $offcanvas-border-color;
//   transform: translateX(100%);
// }

// .offcanvas-top {
//   top: 0;
//   right: 0;
//   left: 0;
//   height: $offcanvas-vertical-height;
//   max-height: 100%;
//   border-bottom: $offcanvas-border-width solid $offcanvas-border-color;
//   transform: translateY(-100%);
// }

// .offcanvas-bottom {
//   right: 0;
//   left: 0;
//   height: $offcanvas-vertical-height;
//   max-height: 100%;
//   border-top: $offcanvas-border-width solid $offcanvas-border-color;
//   transform: translateY(100%);
// }