<div class="container" id="container">
  <div class="item" id="one">1</div>
  <div class="item" id="two">2</div>
  <div class="item" id="three">3</div>
  <div class="item" id="four">4</div>
</div>
<div class="controls">
  <table>
    <tr>
      <td>One:</td>
      <td><input type="text" value="0" onkeyup="var item=document.getElementById('one'); item.style.WebkitFlexGrow = this.value; item.style.flexGrow = this.value;"></td>
    </tr>
    <tr>
      <td>Two:</td>
      <td><input type="text" value="0" onkeyup="var item=document.getElementById('two'); item.style.WebkitFlexGrow = this.value; item.style.flexGrow = this.value;"></td>
    </tr>
    <tr>
      <td>Three:</td>
      <td><input type="text" value="0" onkeyup="var item=document.getElementById('three'); item.style.WebkitFlexGrow = this.value; item.style.flexGrow = this.value;"></td>
    </tr>
    <tr>
      <td>Four:</td>
      <td><input type="text" value="0" onkeyup="var item=document.getElementById('four'); item.style.WebkitFlexGrow = this.value; item.style.flexGrow = this.value;"></td>
    </tr>
  </table>
</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: 800px;
  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: 5em;
  color: #594255;
}

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

input {
  width: 50px;
}