伪类加在 .search-bar .place-holder 这个元素可以吗

.search-bar .place-holder::before {

    content: ' ';

    display: block;

    width: 0.373333rem;

    height: 0.373333rem;

    background-image: url('../img/searchIcon.png');

    background-size: cover;

    top: 0.213333rem;

    left: 0.266667rem;

    position: absolute;

}