.#{$prefix}fade {

@include transition($transition-fade);

&:not(.#{$prefix}show) {
  opacity: 0;
}

}

.#{$prefix}collapse {

&:not(.#{$prefix}show) {
  display: none;
}

}

.#{$prefix}collapsing {

position: relative;
height: 0;
overflow: hidden;
@include transition($transition-collapse);

}