[HTML] Conditional comments Determine browser

<!--[if! ie]><!--> In addition to IE can be recognized <!--<! [endif]-->
<!--[if ie]> all IE recognizable <! [endif]-->
<!--[if IE 6]> only IE6 recognizable <! [endif]-->
<!--[if Lt IE 6]> IE6 and IE6 The following versions are recognized <! [endif]-->
<!--[if GTE IE 6]> IE6 and IE6 above are recognized <! [endif]-->
<!--[if IE 7]> only IE7 recognizable <! [endif]-->
<!--[if Lt IE 7]> IE7 and IE7 The following versions are recognized <! [endif]-->
<!--[if GTE IE 7]> IE7 and IE7 above are recognized <! [endif]-->
<!--[if IE 8]> only IE8 recognizable <! [endif]-->
<!--[if IE 9]> only IE9 recognizable <! [endif]->

Project	Example	Description
!	[If! IE]	The NOT operator. This was placed immediately in front of the feature, operator, or subexpression to reverse the B Oolean meaning of the expression. Not operator. This is the meaning of a Boolean expression that swings immediately in front of the function , operator , or sub-expression .
Lt	[If Lt IE 5.5]	The Less-than operator. Returns true if the first argument is less than the second argument. Less than operator. Returns true if the first argument is less than the second argument.
Lte	[If LTE IE 6]	The Less-than or equal operator. Returns true if the first argument is less than or equal to the second argument. Less than or equal to the operation. Returns true if the first parameter is less than or equal to the second argument.
Gt	[If GT IE 5]	The Greater-than operator. Returns true if the first argument is greater than the second argument. Greater than operator. Returns true if the first argument is greater than the second argument.
Gte	[If GTE IE 7]	The Greater-than or equal operator. Returns true if the first argument is greater than or equal to the second argument. Greater than or equal to the operation. Returns true if the first parameter is greater than or equal to the second argument.
( )	[If! (IE 7)]	subexpression operators. Used in conjunction with the Boolean operators to create more complex expressions. Sub-expression operator. Used in with Boolean operators to create more complex expressions.
&	[If (GT IE 5) & (LT IE 7)]	The AND operator. Returns true if all subexpressions evaluate to True And operator. Returns true if all sub-expressions evaluate to True
|	[If (IE 6) | (IE 7)]	The OR operator. Returns true if any of the subexpressions evaluates to True. Or operator. Returns true if the sub-expression evaluates to True.

<!--[If Lt IE 9]>
Load CSS1
<!--[else]>
Load CSS2
<! [endif]-->
This is effective, but in HTML validator, error, because this does not conform to XHTML 1.1 specification,
If the Else statement is removed, it is correct.

Method 1:

Load CSS2
<!--[If Lt IE 9]>
Load the CSS1 (you can put the rewrite to write here).
<! [endif]-->

[HTML] Conditional comments Determine browser