JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent">
    <div class="body">body of your parent<br/>body<br/>body</div>
    <div class="footer">footer</div>
</div>

CSS

.parent{
    width: 300px; /* your parent width */
    background-color: orange;    
    margin: 0 auto;
}
.footer{
    height: 50px;
    background-color: yellow;
    position:absolute;
    left: 0px;
    right: 0px;
}