CSS Conditional comments

<!--[if IE]>
According to the conditional comment this is Internet Explorer<br />
<![endif]-->

<!--[if IE 5]>
According to the conditional comment this is Internet Explorer 5<br />
<![endif]-->

<!--[if IE 5.0]>
According to the conditional comment this is Internet Explorer 5.0<br />
<![endif]-->

<!--[if IE 5.5]>
According to the conditional comment this is Internet Explorer 5.5<br />
<![endif]-->

<!--[if IE 6]>
According to the conditional comment this is Internet Explorer 6<br />
<![endif]-->

<!--[if IE 7]>
According to the conditional comment this is Internet Explorer 7<br />
<![endif]-->

<!--[if gte IE 5]>
According to the conditional comment this is Internet Explorer 5 and up<br />
<![endif]-->

<!--[if lt IE 6]>
According to the conditional comment this is Internet Explorer lower than 6<br />
<![endif]-->

<!--[if lte IE 5.5]>
According to the conditional comment this is Internet Explorer lower or equal to 5.5<br />
<![endif]-->

<!--[if gt IE 6]>
According to the conditional comment this is Internet Explorer greater than 6<br />
<![endif]-->

출처: http://www.quirksmode.org/css/condcom.html