Why is the width and height of the div set to 0 when the display property is set to inline?
<html>
<head>
<style>
.c
{
width: 300px;
height: 50px;
margin:0px;
padding:0px;
}
#a
{
display:inline;padding:0px; margin:0px;width:100px;height:20px;
}
</style>
</head>
<body>
<div class="c">
<div id="a" style="background-color:#ff0000;"></div>
</div>
</body>
</html>