JSFiddle - React, Tailwind, and code Playground

HTML

<body>
  <div id="grid"></div>
</body>

CSS

html {
  padding: 0;
  margin: 0;
  width: 100%;
  height: 100%;
}

body {
  padding: 0;
  margin: 0;
  width: 100%;
  height: 100%;
}

#grid {
  width: 100%;
  height: 100%;
  box-sizing: border-box;
  border: 25px solid cornflowerblue;
  display: flex;
  flex-direction: row;
  flex-wrap: wrap;
}

.row {
  width: 100%;
  height: auto;
  margin: 10px;
  box-sizing: border-box;
  border: 1px solid red;
  display: flex;
}

.box {
  flex-grow: 1;
  margin: 10px;
  background: pink;
}

.box2 {
  flex-grow: 1;
  margin: 10px;
  box-sizing: border-box;
  border: 25px solid purple;
  background: orange;
}

JavaScript

$(function() {    
  for(var i = 1; i <= 3; i++) {
    $('<div class="row" id="row' + i + '">').appendTo($('#grid'));
    
    for(var j = 0; j < 3; j++) {
      if(i === 2 && j === 1) {
        $('<div class="box2">').appendTo($('#row' + i));
      } else {
        $('<div class="box">').appendTo($('#row' + i));
      }
    }
  }
});