1

Width & Height
Increase the BLUE BOX'S width & height to fill the dotted area.
Click & hold down the or buttons in the CSS.

<html> <!-- HTML start -->

<head>

<style type="text/css"><!-- CSS start -->

#box-1 {
width: 50px;
height: 50px;
background-color: blue
}
  <!-- CSS end -->
</style>

</head>

<body>

<div id="box-1">   </div>

</body>

</html><!-- HTML end -->