<html>
<head>
<style>
#rectangle {
position: absolute;
right: 0;
bottom: 0;
width: 150px;
height: 200px;
}
</style>
</head>
<body>
<div id='rectangle' style='background-color:red;'></div>
<div id='rectangle' style='background-color:green;'></div>
<div id='rectangle' style='background-color:black;'></div>
</body>
</html>
This code demonstrates three boxes displayed side by side using CSS. The intention is to have these boxes positioned at the bottom-right corner of the page without affecting the rest of the content, accomplished through the use of position:fixed. These chat boxes are intended for communication purposes.