Image resize

HTML

<img src="http://devme.eu/images/categories/css/1.png" class="thumbnail">
<img src="http://devme.eu/images/categories/css/1.png" class="halfsize">
<img src="http://devme.eu/images/categories/css/1.png" class="fullsize">

CSS

.thumbnail {
	height: 100px;
	width: 100px;
}
.halfsize {
	height: 200px;
	width: 200px;
}
.fullsize {
	height: 400px;
	width: 400px;
}