First pass at design change

Settings toggle and links are now in a bar at the bottom of the screen.
Settings card now appears as an overlay. Still needs some work and the
markup is a WIP. Light theme currently looks a bit rubbish too, but the
other themes are ok
Fixed settings card

Settings card now floats like a card and doesn't span whole width of
page
Increased title size and added subtle shadow
Tweaked the light theme

Lightened the overlay for the light theme so it's not as dark