<!DOCTYPE html>
<html>
<head>
<style>
#t1 {
    -moz-tab-size: 4; /* Code for Firefox */
    -o-tab-size: 4; /* Code for Opera 10.6-12.1 */
    tab-size: 4;
}


#t2 {
    -moz-tab-size: 16; /* Code for Firefox */
    -o-tab-size: 16; /* Code for Opera 10.6-12.1 */
    tab-size: 16;
}

</style>
</head>
<body>

<pre id="t1">
I        use        tab-size        4
</pre>

<pre id="t2">
I        use        tab-size        16
</pre>

<p><b>Note:</b> The tab-size property is currently supported in Chrome, Safari 6.1+ and Opera 15+.</p>
<p><b>Note:</b> Firefox supports an alternative, the -moz-tab-size property.</p>
<p><b>Note:</b> Opera 10.6 to 12.1 supports an alternative, the -o-tab-size property.</p>

</body>
</html>