JSFiddle - React, Tailwind, and code Playground

HTML

<div class="content">test</div>
    <div class="SideBarFirst">
        <div>not working for center</div>
    </div>

CSS

.content {width:500px; float : left;}

.SideBarFirst {width:460px; float : right;}

.SideBarFirst div {
    width: 40px;
    margin: 0 auto; 
}