<style>
div {
    margin-bottom: auto;
    margin-top: auto;
    position: absolute;
    background-color: green;
    width: 100px;
}
</style>
<div style="height: 500px; width: 500px; background-color: transparent">
 <div style="top: 10px;"></div>
 <div style="bottom: 10px;"></div>
 <div style="top: 10px; height: 100px"></div>
 <div style="bottom: 10px; height: 100px"></div>
</div>