JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="grid">
    <div class="item red">a</div>
    <div class="item yellow">b</div>
    <div class="item blue">c</div>
  </div>
</div>

CSS

.container {
  width: 320px;
  height: 480px;
  background: black;
  padding:15px;
  margin: 20px auto;
  display: flex;
}

.grid {
  background: white;
  display: flex;
  width: 100%;
  justify-content: flex-start;
  align-items: flex-start;
  flex-direction: row;
  flex-wrap: wrap;
}

.item {
  width: 100%;
  flex-grow: 0;
  flex-basis: 100%;
  align-self: auto;
  align-items: flex-start;
  padding: 10px 0;
}

.red { background: red; }
.yellow { background: yellow; }
.blue { background: blue; }