<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
<style>
#container {
width: 120px;
height: 120px;
background-color: #45d169;
-webkit-transform: rotate(90deg);
-moz-transform: rotate(90deg);
-o-transform: rotate(90deg);
transform: rotate(90deg);
}
</style>
</head>
<body>
<div id="container">some text</div>
</body>
</html>