<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function toggleBlock(id) {
var block = document.getElementById(id);
block.style.display = (block.style.display == '') ? 'block' : '';
}
</script>
<style type="text/css">
div#divr {
display: none;
border: 1px solid #cccccc;
}
</style>
</head>
<body>
<a href="javascript:toggleBlock('divr')">Заголовок, краткий текст</a>
<div id="divr">
Основной, объемный текст
</div>
</body>
</html>