How to remove bottom panel in classic mode of gnome 3.12 ?

[lumin <cdluminate@gmail.com>]

Hi,

My system is updated debian jessie. gnome updated to 3.12 today.
seems that jessie will land on gnome-3.12.
I just want to remove (or hide) the bottom panel in classic mode,
to work with a white coloured gnome.

Searched with google, many result say that this key combination works:
Super + Alt + RightClick
but it just worked on gnome flashback mode (e.g. wheezy gnome 3.4),
instead of *gnome 3.12 classic* mode.

Another way I found that may work is modifying
/usr/share/gnome-shell/theme/gnome-{shell,classic}.css
but I found NOTHING after scanning it several times,
there is only a /* TOP BAR */ section.

Any one knows how to deal with it ?
Thank you. :-)