JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrapper">
  <div id="sidebar">side</div>
  <div id="main">main</div>
</div>

CSS

#sidebar {
    float:left;
    width: 50px;
    background-color: blue;
}
#main {
    width: 150px;
    float:left;
     background-color: yellow;
}
#wrapper {
  margin-left: auto;
  margin-right: auto;
  width: 200px;
}