uniapp页面实现背景铺满一屏

使用伪元素

.login_box {
        content:" ";
        position:absolute;
        left:0;
        right:0;
        top:0;
        bottom:0;
        background: url("../../static/img/loginBak.png") no-repeat center center;
        background-size: 100% 100%;
        z-index:-100;
    }