Result Size: 625 x 664
x
 
<!DOCTYPE html>
<html>
<head>
<style>
#main {
  width: 350px;
  height: 100px;
  border: 1px solid #c3c3c3;
  display: flex;
}
#main div {
  flex-grow: 0;
  flex-shrink: 0;
  flex-basis: 40px;
}
</style>
</head>
<body>
<div id="main">
  <div style="background-color:coral;">Red DIV</div>
  <div style="background-color:lightblue;" id="myBlueDiv">Blue DIV</div>
</div>
<p>Click the "Try it" button to set the value of the flexBasis property to "200px" for the blue div element</p>
<button onclick="myFunction()">Try it</button>
<script>
function myFunction() {
  document.getElementById("myBlueDiv").style.flexBasis = "200px";
}
</script>
</body>
</html>