JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="wrapper">
    <input class="field"/>
    <div>x</div>
  </div>
</div>

CSS

.container {
  border: 1px solid black;
  width: 50px;
  display: inline-block;
}

.wrapper {
  display: inline-flex;
  width: 100%;
  height: 100%;
}

.field {
  width: 100%;
  flex-shrink: 1;
}