Layout Padrão

layoutpadrao.css

#area_conteudo
{
    margin: auto;
    width: 922px;
}

#area_superior
{
    width: 902px;
    color: #666;
    background: #303030;
    text-align: center;
    padding: 10px;
    margin: 10px 0px 5px 0px;
}

#area_flexivel
{
    overflow: auto;
    width: 100%;
    background: #E7E4E3;
    margin-bottom: 5px;
}

#area_lateralesq
{
    display: inline;
    color: #333;
    margin: 0px;
    padding: 10px;
    width: 190px;
    float: left;
    text-align: center;
}

#area_central
{
    float: left;
    color: #666;
    margin: 0px 5px;
    padding: 10px;
    width: 455px;
    display: inline;
    position: relative;
    background: #EEEBEA;
}

#area_lateraldir
{
    display: inline;
    position: relative;
    color: #333;
    margin: 0px;
    padding: 10px;
    width: 190px;
    float: right;
    text-align: center;
}

#area_inferior
{
    clear: both;
    width: 902px;
    color: #666;
    background: #303030;
    margin: 0px 0px 10px 0px;
    padding: 10px;
    text-align: center;
    font-family: Verdana,Arial,Helvetica,sans-serif;
    font-size: 12px;
}

layoutpadrao.html

<div id="area_conteudo">
   <div id="area_superior"></div>
   <div id="area_flexivel">
      <div id="area_lateralesq"></div>
      <div id="area_central"></div>
      <div id="area_lateraldir"></div>
   </div>
   <div id="area_inferior"></div>
</div>