انها محاولة لنفسك - CSS Reference js

<!DOCTYPE html>
<html>
<head>
<style>
#myDIV {
   width: 500px;
   background-color: lightblue;
   overflow: auto;
}
</style>
</head>
<body>

<p>Click the "Try it" button to make sure that the DIV element's height never gets bigger than 100 pixels:</p>

<button onclick="myFunction()">Try it</button>

<div id="myDIV">
  <p>This DIV element does not have a pre-defined height.</p>

  <p>The height of this DIV element depends on its content.</p>

  <p>But if you click the "Try it" button, yo will make sure that this DIV element does not exceed 100 pixels in height.</p>
</div>

<script>
function myFunction() {
   document.getElementById("myDIV").style.maxHeight = "100px";
}
</script>

</body>
</html>