如图，把系统的alert修改为UI指定的样式

使用layui的layer覆盖window.alert方法

<style>
        .layui-layer-title {
            background-color: #fff;
            border-color: #fff;
        }

        .layui-layer-dialog .layui-layer-content {
            padding: 30px auto;
            text-align: center;
        }

        .layui-layer-btn .layui-layer-btn0 {
            width: 100px;
            height: 36px;
            text-align: center;
            line-height: 36px;
            background-color: #0156e2;
            border-radius: 4px;
        }

        .layui-layer-btn .layui-layer-btn0:hover {
            background-color: #0D65F6;
            color: #fff
        }
    </style>
    <script>
        window.alert = alert;
        function alert(msg) {
            layui.use('layer', function () {
                layer.open({
                    title: '提示'
                    , content: msg
                });
            });
        }
    </script>