JSFiddle - React, Tailwind, and code Playground

HTML

<div class="layout">
    <main class="main">
       <nav class="menu">
            <div><div class="menu__item">Item</div></div>
            <div><div class="menu__item">Item</div></div>
            <div><div class="menu__item">Item</div></div>
            <div><div class="menu__item">Item</div></div>
      </nav>

      <section class="main__content">
        Some Content
      </section>

    </main>
</div>

CSS

.layout {
    height: 100vh;
    display: flex;
    flex-direction: column;
}

.main {
    display: flex;
}

.menu {
    display: flex;
    border-right: solid 3px red;
    width: 258px;
    flex-direction: column;
}

.menu__item {
    height: 340px;
    width: 240px;
    margin: 10px;
    background: #aaaaaa;
}