JSFiddle - React, Tailwind, and code Playground

HTML

<div class="flex-container">
    <div class="col column">
        <div class="content red"></div>
        <div class="content blue"></div>
    </div>
    <div class="col">
        <div class="content green"></div>
    </div>
</div>

CSS

.flex-container {
   display:flex;
   width:100px;
   height:100px;
}
.col {
   flex:1;
   display:flex;
}
.column {
   flex-direction:column;
}
.content {
   flex:1;
}
.red {
    background-color:red;
}
.blue {
    background-color:blue;
}
.green {
    background-color:green;
}