Make the menu appear when introHeight is large

[er-vin]

To that effect, introduce a new hero is-bottom-menu class which uses
viewport height at 80% to give room for the menu (can't be perfect since
we of course can't mix vh and rem units). Also make sure we use that
class instead of is-large when introHeight is set to large.

That should match the behavior discussed previously.

[hanzei]

Hey @er-vin,

Thanks for the PR! Would you mind sharing some before/after screenshots?

[er-vin]

Yes, sure, here they are. First without the patch, full page and viewport on load:

And now with the patch, full page and viewport on load:

Now obviously the problem with my approach is that if the viewport is not tall enough, the menu might still be out. That's because I found no good way to express the menu height in term of the vh unit. Suggestions welcome but I doubt we can do it without switch the menu to the vh unit as well, which will probably do strange things on very tall viewports.

[er-vin]

For the record I didn't find another way of doing it which wouldn't involve vh or doing weird things to the menu (as in switching it to vh which would have other side-effects). So expect if you got suggestions I think this patch will be definitive.

[victoriadrake]

Hey @er-vin!

Thank you for the PR. I believe your goal is better addressed with changes made in #137 which corrects the index template.

The hero height is set using Bulma's styling, and I believe the value you're after is "fullheight". This will show the navbar at the bottom of the hero regardless of the viewport height.

[er-vin]

OK, I admit I'm slightly confused because your decision now contradicts what you said on my previous attempt at fixing this which was more similar to #137. It was shutdown at the time. Oh well... :-)

I'm totally fine with #137, obviously I far prefer that approach. Really looking forward to it being merged.