/*Struttura base pagina*/
#bordo-sinistra{
float:left;
width: 15px;
height: 540px;
/*border: 1px solid red;*/
margin: 0;
background-color: red;
}

#bordo-destra{
float:right;
width: 15px;
height: 540px;
/*border: 1px solid red;*/
margin: 0;
background-color: red;
}

#main_page{
height: 540px;
/*border: 1px solid yellow;*/
margin: auto;
background-color: blue;
}

/** HTML **/
< div id="bordo-sinistra" >
< / div >
< div id="bordo-destra" >
< / div >
< div id="main_page" >
< / div >