JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
<li>1</li>
<li>2</li>
<li>3</li>
<li>4</li>
<li>5</li>
<li>6</li>
<li>7</li>
<li>8</li>
<li>9</li>
<li>10</li>
<li>11</li>
<li>12</li>
</ul>

CSS

ul{
  
  margin: 0;
  padding: 0;
  display: -webkit-box;      /* OLD - iOS 6-, Safari 3.1-6 */
  display: -webkit-flex;
  display: -moz-flex;
  display: -ms-flex;
  display: -o-flex;
  display: flex;
  -webkit-flex-direction: column;
  -moz-flex-direction: column;
  -ms-flex-direction: column;
  flex-direction: column;
  -webkit-flex-wrap: wrap;
  -moz-flex-wrap: wrap;
  -ms-flex-wrap: wrap;
  flex-wrap: wrap;
  background-color: #e1ffb8;
  width: auto;
  height:150px; 
  min-height:150px;
  max-height:150px;
  
  margin: 0 auto;
}

li{

    -webkit-box-pack: center;
    -webkit-box-align: center;
    -moz-box-pack: center;
    -moz-box-align: center;
    -ms-box-pack: center;
    -ms-box-align: center;
	-webkit-justify-content: center;
    -moz-justify-content:center;
	-ms-justify-content:center;
	justify-content: center;
    
    height: 50px;
    width:50px;
    background-color: #ff5368;
    text-align: center;
    
    /* Added this: */
    min-height: 50px;
    min-width: 50px;
    -webkit-box-flex: 1;
    -moz-flex: auto;
    -webkit-flex: auto;
    flex: auto;
}