<!DOCTYPE html>
<html>
<head>
<style>
img {
width:100%;
}
</style>
</head>
<body>
<p>It is better to use the style attribute (instead of the width and height attributes), because it prevents
internal or external styles sheets to change the original size of an image:</p>
<img src="html5.gif" alt="HTML5 Icon" style="width:128px;height:128px;">
<img src="html5.gif" alt="HTML5 Icon" width="128" height="128">
</body>
</html>