My WordPress menu based on Twitter bootstrap creates menu-item and not page-item

This is an example of CSS code which works with one specific theme.

You may need to change the classes depending on your theme.

.nav-primary .current-menu-item > a  {
color: blue;
background-color: white;
}

This will highlight the background color of the current menu item to white and you can also change the font color which in this case is blue.