JSFiddle - React, Tailwind, and code Playground

HTML

<div class="calselect">
  <span class="txtleft"><a href="?d=-1"><button class="btn--primary"><i class="icon-arrow--left"></i></button></a></span>
  <span class="txtcenter">milieu</span>
  <span class="txtright"><a href="?d=+1"><button class="btn--primary"><i class="icon-arrow--right"></i></button></a></span>
</div>

CSS

body {
	width: 100%;
	margin: 0;
	font-family: Arial;
}

.calselect {
	background-color: #aaa;
  display: flex;
}

.txtcenter {
  flex: 1 1;
}