[TYPO3] fdfx_2cols div layout style

[rocky]

Hey,

I'm using fdfx_2cols extention div layout to make 2 column page content.
Below is my CSS, The problem is I need to put -115px to make the middle 
column reside with the left column. Is there a good way to altar this 
because some pages -110px is far more too left-offsided.

########################
/***********************************************STYLE FIR 2 
clomun*******************/
div.tx-fdfx2cols-pi1{
    border: 2px solid #336;
    margin-bottom:10px;
}
/* Layout 1 */
div.c2l1d-left{
    width:50%;
    margin:0;
    border:2px solid #3f3;
}
div.c2l1d-middle{
   /* left:0px;*/
    position:relative;
    padding: 0px;
    width:50%;
    border:1px solid blue;
    white-space:normal;
    margin-left:-115px;
}
#####################################

Thanks a lot!
Rocky