JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent-div">
  <div class="first-child">
    <span class="block">Item</span>
    <span class="block">Item</span>
    <span class="block">Item</span>
  </div>
  <div class="second-child">
    <span class="block">Content here</span>
    <span class="block">Content here</span>
    <span class="block">Content here</span>
    <span class="block">Content here</span>
    <span class="block">Content here</span>
    <span class="block">Content here</span>
    <span class="block">Content here</span>
    <span class="block">Content here</span>
    <span class="block">Content here</span> 
  </div>
</div>

CSS

.parent-div {
  background:green;
  display: inline-block;
  width: 100%;
}

.first-child,
.second-child {
  float: left;
}

.first-child {
  width: 50px;
  border-right: 2px solid red;
}

.second-child {
  padding-left: 10px;
}

.block {
  display: block;
}