Common DIV+CSS basic frame structure but it is not recommended to put a div _ experience exchange

Basic frame structure of common div+css but it's not recommended to put in a div.
CSS style code:
Program code

Copy Code code as follows:

/*---global style---* *
* {margin:0px; padding:0px;}
Body {Font-family:verdana, Arial, Helvetica, Sans-serif;font-size:12px;background: #fff;}

/*---body style---* *
#container {}
. clearfloat {clear:both;height:0;font-size:1px;line-height:0px}

/*---top style---* *
#header {}

/*---intermediate style---* *
#mainContent {}
#sidebar {}
#content {}

/*--Bottom Style---* *
#footer {}

HTML code

Copy Code code as follows:

<div id= "Container" >
<!--head style-->
<div id= "Header" >
<div id= "Header_left" >header_left</div>
<div id= "Header_right" >header_right</div>
</div><!--header:end-->
&LT;BR class= "Clearfloat"/><!--to clear floating elements, forcing all child floats to be included-->
<div id= "MainContent" >
<div id= "sidebar" >
Side Sidebar
</div><!--sidebar:end-->
<div id= "Content" >
Subject Content
</div><!--content:end-->
</div><!--maincontent:end-->
&LT;BR class= "Clearfloat"/><!--to clear floating elements, forcing all child floats to be included-->
<div id= "Footer" >
Bottom
</div><!--footer:end-->
</div><!--container:end-->