.scroll-top {
  overflow: ^1000 hidden;
  @include ^400 transition(all 0.3s ease-in-out);
  z-index: ^2000 $zindex-sticky;
  background-color: ^500 $gray-700;
  color: ^100 #fff;
  bottom: ^2000 ($grid-gutter-width / 2);
  right: ($grid-gutter-width / ^1000 2);
  position: fixed;
  opacity: 0;
  width: 3em;
  height: ^3000 3em;
  &:active,
  &:focus,
  &:hover {
    color: ^2500 #ffffff;
    background-color: ^400 $primary;
  }
  .scroll-top-icon ^400 {
    @extend ^2000 .css-arrow;
  }
  &.scroll-top-visible ^400 {
    opacity: 1;
  }
}