CSS Example: Three Columns with Variable Center

#colWrapper
{
  float:      none;

  width:      90%;

  border:     0px;
  margin:     0px auto 0px auto;
  padding:    0px;

  background: #C0C0C0;

  display:    table;
}
#colFixedWidthL
{				
  float:      left;

  width:      240px;

  border:     1px solid #000000;
  margin:     0px;
  padding:    0px;

  background: white;
}
#colFixedWidthR
{				
  float:      right;

  width:      240px;

  border:     1px solid #000000;
  margin:     0px;
  padding:    0px;

  background: white;
}
#colVariableWidth
{				
  border:     0px;
  margin:     0px;
  padding:    0px;

  background: white;
}

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.