body {
    /* 引入你的背景图 */
    background-image: url(../../../img/member/publics/beijingdediyige.png)!important;
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    background-repeat: no-repeat;
    /* 备用背景色，防止图片加载慢时大白屏 */
    background-color: #000!important;
}

/* 如果想要你之前那个粉紫渐变的效果，可以叠加一个半透明层 */
body::before {
    content: "";
    position: fixed;
    inset: 0;
    background: linear-gradient(135deg, rgba(168, 237, 234, 0.2) 0%, rgba(254, 214, 227, 0.5) 100%);
    z-index: -1;
}