JSFiddle - React, Tailwind, and code Playground

HTML

<div id="a">
  <div>a</div>
  <div>b</div>
  <div>c</div>
  <div>d</div>
  <div>e</div>
  <div>f</div>
  <div>g</div>
  <div>h</div>
  <div>i</div>
</div>

CSS

#a {
    border: 1px solid gray;
    display: flex;
    flex-wrap: wrap;
    justify-content: space-around;
    width: 450px;
}
#a > div {
    border: 1px solid red;
    width: 100vw;
    max-width: 33%;
    box-sizing: border-box;
}