<!DOCTYPE html>
<html>
<head>
<style>
input:-moz-read-only { /* For Firefox */
background-color: yellow;
}
input:read-only {
background-color: yellow;
}
</style>
</head>
<body>
<h3>A demonstration of the :read-only selector.</h3>
<p>A normal input element:<br><input value="hello"></p>
<p>A readonly input element:<br><input readonly value="hello"></p>
<p>The :read-only selector selects form elements with a "readonly" attribute.</p>
<p><strong>Note:</strong> The :read-only selector is not supported in Internet Explorer.</p>
<p><strong>Note:</strong> Firefox supports an alternative, the :-moz-read-only property.</p>
</body>
</html>