JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="obal">
    <div class="item">1</div>
    <div class="item">2</div>
    <div class="item">3</div>
    <div class="item">4</div>
    <div class="item">5</div>
    <div class="item">6</div>
    <div class="item">7</div>
        <div class="item">7</div>
            <div class="item">7</div>
                <div class="item">7</div>
                    <div class="item">7</div>
                        <div class="item">7</div>
                            <div class="item">7</div>
                                <div class="item">7</div>
  </div>
</div>

CSS

* {
  font-size: 30px;
  font-weight: bold;
  font-family: sans-serif;
}

.container {
  width: 800px; 
  height: 600px;
  margin-left: auto;
  margin-right: auto;
  box-sizing: border-box;
  border: 10px solid black;
}

.obal {
  box-sizing: border-box;
  display: grid;
  border: 10px solid red;
  grid-template-columns: 2fr 2fr 6fr;
  grid-template-rows: 20% 1fr;
  grid-gap: 20px;
  height: 100%;
}

.item {
  background: #ffaa00;
  display: grid;
  justify-content: center;
  align-content: center;
}