JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="a"></div>
    <div class="b"></div>
</div>

CSS

.a
{
    width:100px;
    height:400px;
    display:inline-block;
    background-color:blue;
    vertical-align: top;
}
.b
{
    width:400px;
    height:600px;
    display:inline-block;
    margin-left:30px;
    background-color: green;
}