[IT-1383] Make footer sticky to bottom
[IT-1383] Make footer sticky to bottom

Even on short pages, the footer now sticks to the bottom of the viewport.
The behavior doesn't change for long sites.

iteratec/OpenSpeedMonitor,iteratec/OpenSpeedMonitor,IteraSpeed/OpenSpeedMonitor,iteratec/OpenSpeedMonitor,IteraSpeed/OpenSpeedMonitor,iteratec/OpenSpeedMonitor,IteraSpeed/OpenSpeedMonitor,iteratec/OpenSpeedMonitor