Header disappears on screens shorter than 680px

[GusRuss89]

Expected behaviour

Be able to see and interact with the header (search, balance, ID).

Actual behaviour

Header disappears on screens shorter (in height) than 680px.

Steps to reproduce

1. Open Lisk Hub dashboard.
2. Resize viewport to less than 680px tall.

Note this seems to only affect the dashboard screen.

My 13" Macbook Pro Retina, set to default scale, with Chrome's tabs, address bar and bookmarks bar visible, ends up less than 680px tall. This is a pretty common screen size.

[GusRuss89]

Another screen-height issue.

On the register/create lisk ID flow, once I'm presented with my Lisk ID, the "Get Passphrase" button is not visible. I can scroll down within the #generatorContainer panel, but it certainly isn't immediately obvious that I'm supposed to scroll.