JSFiddle - React, Tailwind, and code Playground

HTML

<div class="layout">
  <div class="sidebar sidebar--left">left</div>
  <div class="content">content</div>
  <div class="sidebar sidebar--right">right</div>
</div>

CSS

*,
*:before,
*:after {
  box-sizing: border-box;
}

html, body {
  min-height: 100%;
  height: 100%;
}

.layout {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-start;
  height: 100%;
}

.content {
  flex: 1 1;
  min-width: 200px;
  align-self: stretch;
}

.sidebar {
  flex: 0 0 300px;
}

.content,
.sidebar {
  border: 1px solid #333;
  background-color: #eee;
}