实现动效省略号

.loading {
 color: #999999;
  &:after {
    overflow: hidden;
    display: inline-block;
    vertical-align: bottom;
    animation: ellipsis steps(4, end) 1500ms infinite;
    content: '\2026'; /* ascii code for the ellipsis character */
    width: 0px;
  }
}
@keyframes ellipsis {
  to {
    width: 1.25em;
  }