Не резиновая резина

<div id="mainbody" class="container_12">
						<div id="main" class="grid_<?php echo $main_weidth ?>">
						<?php cmsModule('maintop'); ?>
						<?php cmsBody(); ?>
						<?php cmsModule('mainbottom'); ?>
						</div>
						<?php if ($mod_count['leftbar']) { ?>
						<div class="grid_4" id="leftbar"><?php cmsModule('leftbar'); ?></div>
						<?php } ?>
						<?php if ($mod_count['sidebar']) { ?>
						<div class="grid_4" id="sidebar"><?php cmsModule('sidebar'); ?></div>
						<?php } ?>

#main{padding:0 200px}
#sidebar {
	float: left;
	margin-right: -3px;
	margin-left: -200px;
	position: relative;
}
#leftbar{
	float: left;
	margin-left: -100%;
	position: relative;}
 

.container_12 .grid_4{width:200px;}.container_12 .grid_8{width:auto}

<div id="main" class="grid_<?php echo $main_weidth ?>">

<div id="main" class="grid_8">