JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent-container">
  <div class="child-container">
    <span class="color-block"></span>
    <span>This is a long long long long long text.</span>
  </div>
</div>

CSS

.parent-container {
  display: flex;
  background: orange;
}

.child-container {
  display: flex;
  background: green;
}

.color-block {
  background: yellow;
  flex: 0 0 0;
  padding-left: 15px;
  align-self: stretch;
}