This Can be Done by Style Property.
<!DOCTYPE html>
<html>
<head>
<style>
#main {
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>
</body>
</html>
Its Result will be :
Enjoy... Please Note: This works in Higher version of CSS (>3.0).