레이아웃 $Content CSS 깨지는 문제..

<div style="width:1200px; margin:auto;">
    <div>
<div style="float: left;">
<a href=""><img style="margin-left: auto; margin-right: auto; display: block;" src="http://s.nx.com/s2/game/arpiel/obt/common/img_logo.png"></a>
</div>
        <div>
<!-- GNB -->
<nav class="gnb" id="gnb">
<ul>
<li loop="$GNB->list=>$key1,$val1" class="active"|cond="$val1['selected']">
<a href="{$val1['href']}" target="_blank"|cond="$val1['open_window']=='Y'">{$val1['link']}</a>
<ul id="sub_menu" cond="$val1['list']">
<li loop="$val1['list']=>$key2,$val2" class="active"|cond="$val2['selected']"><a href="{$val2['href']}" target="_blank"|cond="$val2['open_window']=='Y'">{$val2['link']}</a></li>
</ul>
</li>
</ul>
</nav>
<!-- /GNB -->
</div>
    </div>
<!-- 미들 컨텐츠 -->
<div style="background:white;border: 1px solid #BDBDBD; margin-bottom: 100px;" >
<div>
<div style="float:left;">
<img src="http://img.danawa.com/cp_images/service/79/3060286/151126-risell-pp006.jpg" width="800" height="400">
</div>
<div style="float: left; width:398px;">
<!--@if($layout_info->layout_gamestart)-->
<img class="zbxe_widget_output" widget="G_login_info" skin="Game_login" colorset="default" widget_cache="0m" ncenter_use="yes" />
<!--@else-->
<!--@end-->
</div>
<!--플로트 해제-->
<div style="clear:both;"></div>
</div>

<!--메인 컨텐츠 -->
<div style="width:1100px; background-color:white; margin:auto;">
{$content}
</div>
</div>
</div>