<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
<style>
.example {
line-height: 150px;
border: 1px solid #000;
display: inline-block;
vertical-align: middle;
}
</style>
</head>
<body>
<span class="example">
This is a vertically aligned text.
</span>
</body>
</html>