Dropdown menu WooThemes

Hi,

I got the theme Shelflife from WooThemes running on my website.
If you hoover over the menu, there will appear a dropdown menu.
This menu drops down, and from the first ‘link’ it goes to the RIGHT >>

Now, what i want is to get this menu to drop DOWN. So people don’t have to steady their arm and slightly go to the right, because if they get the mouse of the dropdown, the menu dissapears.

If you don’t understand what i mean, go to Shelflife theme and hoover over ‘Checkout’.

I really don’t know how i can change this. Please help me.
I find this in the css file:

/* 2.2.1 Drop-down menus */
.nav li ul {
  position: absolute;
  left: -999em;
}
.nav li:hover,
.nav li.hover {
  position: static;
}
.nav li:hover ul ul,
.nav li.sfhover ul ul,
.nav li:hover ul ul ul,
.nav li.sfhover ul ul ul,
.nav li:hover ul ul ul ul,
.nav li.sfhover ul ul ul ul {
  left: -999em;
}
.nav li:hover ul,
.nav li.sfhover ul,
.nav li li:hover ul,
.nav li li.sfhover ul,
.nav li li li:hover ul,
.nav li li li.sfhover ul,
.nav li li li li:hover ul,
.nav li li li li.sfhover ul {
  left: auto;
}

I don;t know if this is the right code, if it isn’t please tell me.

Thanks in advance ??