function showfeatures(index)
{
  for (i=0;i<8;i++)  
    document.getElementById('tab'+i).style.display='none';

  for (i=1;i<8;i++) {
    document.getElementById('featurebox-li'+i).style.background='transparent';
    document.getElementById('featurebox-li'+i).style.color ='#393939'; 
  }

  document.getElementById('tab'+index).style.display = 'block';
  document.getElementById('featurebox-li'+index).style.backgroundColor = '#393939';
  document.getElementById('featurebox-li'+index).style.color = '#fff';
}