JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <form method="post" style="margin: 0.7vw 0 0.7% 1vw;">
    <input class="comment" type="text">
    <input type="submit">
  </form>

  <div class="square">
  </div>
  <div class="square">
  </div>
  <div class="square">
  </div>
  <div class="square">
  </div>
  <div class="square">
  </div>
  <div class="square">
  </div>
  <div class="square">
  </div>
  <div class="square">
  </div>
  <div class="square">
  </div>
  <div class="square">
  </div>
  <div class="square">
  </div>
  <div class="square">
  </div>
  <div class="square">
  </div>
  <div class="square">
  </div>
</div>

CSS

.container {
  display: flex;
  flex-wrap: wrap;
}

.container:after {
  flex: 1;
  content: '';
}

.container form {
  width: 100%;
  display: flex;
}

.container .comment {
  flex: 1;
}

.square {
  padding: 10px;
  width: calc(100% / 9);
  margin: 0.7vw 0 0.7% 1vw;
  background: red;
}