<!DOCTYPE html>
<html>
<head>
<style>
#main {
width: 250px;
height: 100px;
border: 1px solid #c3c3c3;
display: flex;
}
#main div {
flex-grow: 0;
flex-shrink: 0;
flex-basis: 50px;
}
#myBlueDiv {
animation: mymove 5s infinite;
}
@keyframes mymove {
50% {flex-basis: 200px;}
}
</style>
</head>
<body>
<h1>Animation of flex-basis</h1>
<p>Gradually change the flex-basis property of the BLUE div from 50px to 200px, and back:<p>
<div id="main">
<div style="background-color:coral;">RED</div>
<div style="background-color:lightblue;" id="myBlueDiv">BLUE</div>
</div>
</body>
</html>