<div class="container" id="container">
  <div class="item big">1</div>
  <div class="item">2</div>
  <div class="item small">3</div>
  <div class="item big">4</div>
  <div class="item">5</div>
  <div class="line" id="line"></div>
</div>
<div class="controls">
  <input type="radio" name="align-items" id="flex-start" 
         onclick="
                  var container=document.getElementById('container'); 
                  container.style.WebkitAlignItems = 'flex-start';
                  container.style.alignItems = 'flex-start'; 
                  var line = document.getElementById('line'); 
                  line.style.visibility = 'hidden';  
                  ">
  <label for="flex-start">align-items: flex-start;</label>
  <br>
  <input type="radio" name="align-items" id="flex-end" 
         onclick="
                  var container=document.getElementById('container'); 
                  container.style.WebkitAlignItems = 'flex-end'; 
                  container.style.alignItems = 'flex-end'; 
                  var line = document.getElementById('line'); 
                  line.style.visibility = 'hidden';  
                  ">
  <label for="flex-end">align-items: flex-end;</label>
  <br>
  <input type="radio" name="align-items" id="center" 
         onclick="
                  var container=document.getElementById('container'); 
                  container.style.WebkitAlignItems = 'center'; 
                  container.style.alignItems = 'center'; 
                  var line = document.getElementById('line'); 
                  line.style.visibility = 'hidden';  
                  ">
  <label for="center">align-items: center;</label>
  <br>
  <input type="radio" name="align-items" id="baseline" 
         onclick="
                  var container=document.getElementById('container'); 
                  container.style.WebkitAlignItems = 'baseline'; 
                  container.style.alignItems = 'baseline'; 
                  var line = document.getElementById('line'); 
                  line.style.visibility = 'visible'; 
                  ">
  <label for="baseline">align-items: baseline;</label>
  <br>
  <input type="radio" name="align-items" id="stretch" 
         onclick="
                  var container=document.getElementById('container');
                  container.style.WebkitAlignItems = 'stretch';  
                  container.style.alignItems = 'stretch'; 
                  var line = document.getElementById('line'); 
                  line.style.visibility = 'hidden'; 
                  " checked>
  <label for="stretch">align-items: stretch;</label>
</div>
body {
  background-color: #F5F5F5;
  color: #555;
  font-size: 1.1em;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
}

hr {
  margin: 50px 0;
}

.container {
  margin: 150px auto;
  max-width: 840px;
  height: 400px;
  padding: 20px;
  -webkit-display: -webkit-box;
  -webkit-display: -webkit-flex;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  background-color: #594255;
  position: relative;
}

.line {
  height: 1px;
  width: 100%;
  border-bottom: 2px solid deepPink;
  position: absolute;
  top: 120px;
  left: 0;
  visibility: hidden;
}

.item {
  background-color: #fff;
  width: 100px;
  margin: 1%;
  text-align: center;
  line-height: 100px;
  font-weight: bold;
  font-family: sans-serif;
  font-size: 4em;
  color: #594255;
}

.big {
  width: 150px;
  font-size: 5em;
}

.small {
  font-size: 2em;
}

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