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<!DOCTYPE html>
<html>
<head>
<style> 
#myDIV {
  width: 50%;
  background-color: lightblue;
  overflow: auto;
  border: 1px solid black;
  animation: mymove 5s infinite;
}
@keyframes mymove {
  50% {min-width: 800px;}
}
</style>
</head>
<body>
<h1>Animation of min-width</h1>
<p>Change the min-width from "none" to 800px, and back to "none":<p>
<p><strong>Note:</strong> The min-width property overrides the width property.</p>
<div id="myDIV">
  <p>This DIV element has a pre-defined width: 50%.</p>
  <p>An animation will gradually change the min-width to 800 pixels.</p>
</div>
</body>
</html>