xiaoshi-wx/node_modules/wux-weapp/example/pages/backdrop/index.wxss

/* pages/backdrop/index.wxss */
.custom-content {
    position: absolute;
    top: 50%;
    left: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 150px;
    height: 150px;
    margin-top: -75px;
    margin-left: -75px;
    padding: 15px;
    background: #fff;
    border-radius: 6px;
}