JSFiddle - React, Tailwind, and code Playground

HTML

<div id="outer">
    
    <div id="first">&nbsp;</div>
    
    <div id="second">&nbsp;</div>
    
</div>

CSS

#outer {
   display: -webkit-flex;
   display: flex;
   -webkit-flex-direction: column; 
   flex-direction: column;
   border:solid red 1px
}

#first {
    background-color: red;
    width:100px;
    right:10px;
    align-self: flex-end;
    margin-right: 10px;
}

#second {
    background-color: green;
    width:100px;
}