<div class="container" id="container">
  <div class="item big">1</div>
  <div class="item">2</div>
  <div class="item">3</div>
  <div class="item big">4</div>
  <div class="item">5</div>
</div>
<div class="controls">
  <input type="radio" name="justify-content" id="flex-start" 
         onclick="
                  var container=document.getElementById('container'); 
                  container.style.WebkitJustifyContent = 'flex-start'; 
                  container.style.justifyContent = 'flex-start'; 
                  " checked>
  <label for="flex-start">justify-content: flex-start;</label>
  <br>
  <input type="radio" name="justify-content" id="flex-end" 
         onclick="
                  var container=document.getElementById('container'); 
                  container.style.WebkitJustifyContent = 'flex-end'; 
                  container.style.justifyContent = 'flex-end'; 
                  ">
  <label for="flex-end">justify-content: flex-end;</label>
  <br>
  <input type="radio" name="justify-content" id="center" 
         onclick="
                  var container=document.getElementById('container'); 
                  container.style.WebkitJustifyContent = 'center'; 
                  container.style.justifyContent = 'center'; 
                  ">
  <label for="center">justify-content: center;</label>
  <br>
  <input type="radio" name="justify-content" id="space-between" 
         onclick="
                  var container=document.getElementById('container'); 
                  container.style.WebkitJustifyContent = 'space-between';
                  container.style.justifyContent = 'space-between';
                  ">
  <label for="space-between">justify-content: space-between;</label>
  <br>
  <input type="radio" name="justify-content" id="space-around" 
         onclick="
                  var container=document.getElementById('container'); 
                  container.style.WebkitJustifyContent = 'space-around'; 
                  container.style.justifyContent = 'space-around'; 
                  ">
  <label for="space-around">justify-content: space-around;</label>
</div>
body {
  background-color: #F5F5F5;
  color: #555;
  font-size: 1.1em;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
}

.container {
  margin: 150px auto;
  width: 840px;
  padding: 20px;
  -webkit-display: -webkit-box;
  -webkit-display: -webkit-flex;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  background-color: #594255;
}

.item {
  background-color: #fff;
  width: 100px;
  height: 100px;
  margin: 1%;
  text-align: center;
  line-height: 100px;
  font-weight: bold;
  font-family: sans-serif;
  font-size: 6em;
  color: #594255;
}

.big {
  width: 150px;
}

.controls {
  background-color: white;
  width: 300px;
  padding: 20px;
  line-height: 150%;
  position: fixed;
  top: 0;
  right: 0;
  border: 1px solid #ddd;
}
Rerun