如何显示绝对或固定div下面的div？

<style>
    .parent {
        position: relative;
        height: 200px;
        width: 200px;
        background-color: lightgray;
    }

    .absolute-div {
        position: absolute;
        top: 100px;
        left: 50px;
        height: 50px;
        width: 100px;
        background-color: red;
    }

    .relative-div {
        position: relative;
        top: 50px;
        left: 50px;
        height: 50px;
        width: 100px;
        background-color: blue;
    }
</style>

<div class="parent">
    <div class="absolute-div"></div>
    <div class="relative-div"></div>
</div>