css3方法：未知高度宽度居中

new_gist_file.html

<style>
.tips_layer_wrap {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, .7);
    z-index: 10000;
}

.tips_layer_wrap .tips_layer {
    -webkit-transform: translate(-50%, -50%);
    transform: translate(-50%, -50%);
    padding: 46px 60px;
    background: #fff;
    position: absolute;
    left: 50%;
    top: 50%;
    font-size: 20px;
    color: #000;
    border-radius: 10px;
}
</style>
<div class="tips_layer_wrap">
	<div class="tips_layer">请填写完整信息</div>
</div>