JSFiddle - React, Tailwind, and code Playground

HTML

<div class='page__header'>
  <h1>title</h1>
  <div>
    <input>
  </div>
  <button>some button</button>
</div>

CSS

html, body { height: 100%; }
.page__header {
  background: lightgreen;
  display: flex;
  flex-direction: row;
  flex-wrap: nowrap;
  justify-content: space-between;
  align-content: stretch;
  align-items: stretch;
    height: 30%; 
}
.page__header h1 {
  flex: 1 0;
}

.page__header button {
   order: 5;
}

.page__header div {
  align-self: left;
  order: 2;
  position: relative;
    height: 100%;
}
.page__header div input {
  min-width: 260px;
  padding: 0 1em;
  height: 100%;
  text-transform: uppercase;
}