layui列表页滚动时弹出窗无法居中的解决方案

function x_admin_show(title, url, w, h) {
    if (title == null || title == '') {
        title = false;
    }
    if (url == null || url == '') {
        url = "404.html";
    }
    if (w == null || w == '') {
        w = ($(window).width() * 0.9);
    }
    if (h == null || h == '') {
        h = ($(window).height() - 50);
    }
    parent.layer.open({
        type: 2,
        area: [w + 'px', h + 'px'],
        fix: false, //不固定
        maxmin: true,
        shadeClose: true,
        shade: 0.4,
        title: title,
        content: url
    });
}