JSFiddle - React, Tailwind, and code Playground

HTML

<div class="colunaGrande"></div>
<div class="colunaPequena">
    <ul class="caixas">
        <li class="box"></li>
        <li class="box"></li>
        <li class="box"></li>
        <li class="box"></li>
        <li class="box"></li>
    </ul>
</div>
<div class="colunaPequena">
    <ul class="caixas">
        <li class="box"></li>
        <li class="box"></li>
        <li class="box"></li>
    </ul>
</div>

CSS

.colunaGrande {
    float:left; /* Propriedade adicionada à coluna grande */
    width: 70%;
    max-width: 450px;
    height: 95vh;
    background-color: burlywood;
}

.colunaPequena {
    float:left; /* Propriedade adicionada à coluna pequena */
    width: 15%;
    max-width: 80px;
    border: 1px solid #000;
}

ul.caixas {
    margin: 0;
    padding: 0;
    list-style-type: none;
}
li.box {
    width: 65%;
    height: 30px;
    background-color: #000;
    margin: 10px auto;
}