html tutorial - How to apply CSS opacity in IE7 and IE8 browsers - html5 - html code - html form
Answer: Use Microsoft "alpha filter" property
The opacity property only supported in Internet Explorer 9 and above browsers.The "alpha filter" used to control the transparency of an element in Internet Explorer 8 and earlier versions.
Example
<!DOCTYPE html>
<html lang="en">
<head>
<title>CSS Opacity for IE8 and Lower</title>
<style type="text/css">
p {
filter: alpha(opacity=50);
zoom: 1; /* Fix for IE7 */
opacity: 0.5; /* Standard Syntax */
}
</style>
</head>
<body>
<p><strong>Note:</strong> Alpha filters is Microsoft-only property to control transparency in IE8 and earlier version, however it creates invalid code in your CSS.</p>
</body>
</html>