ant-design/style/components/badge.less

@badge-prefix-cls: ~"@{css-prefix}badge";
@number-prefix-cls: ~"@{css-prefix}number";

.@{badge-prefix-cls} {
  position: relative;
  display: inline-block;
  line-height: 1;

  &-count {
    position: absolute;
    transform: translateX(-50%);
    top: -10px;
    height: 20px;
    border-radius: 10px;
    min-width: 20px;
    background: @error-color;
    color: #fff;
    line-height: 20px;
    text-align: center;
    padding: 0 7px;
    font-size: 12px;
    white-space: nowrap;
    transform-origin: -10% center;
    z-index: 10;
    font-family: tahoma;
    box-shadow: 0 0 0 1px #fff;
    a, a:hover {
      color: #fff;
    }
  }

  &-dot {
    position: absolute;
    transform: translateX(-50%);
    transform-origin: 0px center;
    top: -4px;
    height: 8px;
    width: 8px;
    border-radius: 100%;
    background: @error-color;
    z-index: 10;
    box-shadow: 0 0 0 1px #fff;
  }

  &-zoom-appear,
  &-zoom-enter {
    animation: antZoomBadgeIn .3s @ease-out-back;
    animation-fill-mode: both;
  }

  &-zoom-leave {
    animation: antZoomBadgeOut .3s @ease-in-back;
    animation-fill-mode: both;
  }
}

a .@{badge-prefix-cls} {
  &-count:hover {
    background: tint(@error-color, 20%);
  }
  &-count:active {
    background: shade(@error-color, 5%);
  }
}

.@{number-prefix-cls}{
  overflow: hidden;
  &-only{
    display: inline-block;
    transition: transform .3s @ease-in-out;
  }
}

@keyframes antZoomBadgeIn {
  0% {
    opacity: 0;
    transform: scale(0) translateX(-50%);
  }
  100% {
    transform: scale(1) translateX(-50%);
  }
}

@keyframes antZoomBadgeOut {
  0% {
    transform: scale(1) translateX(-50%);
  }
  100% {
    opacity: 0;
    transform: scale(0) translateX(-50%);
  }
}