Full screen 7x5 grid with Foundation SCSS

Hope there's someone here that have done what I'm currently trying to accomplish. I'm learning some new JS frameworks and I've got an idea to make full screen calendar with topbar fixed as my homepage. This calendar should take full width and full height available on normal monitors.

I've managed to make it full width using Foundation SCSS by changing this in _settings.scss:

$row-width: 100%;
$total-columns: 7;

My main question is - what's the optimal way for creating 5 rows (it's always 5 rows for single month) that will always take full remaining height of the screen? (remaining because of that topbar navigation that is fixed).

I'm ok with SCSS so all suggestions are welcome.

Thanks!