Fix mobile report view UI

[colleenm]

The report view UI should be possible to use on mobile.

Changes sufficient for solving the mobile view:

Mobile and desktop changes

• [x] Change right-side hamburger menu to kebab (options) menu (see mocks) on both mobile and desktop

Mobile-only changes

• [x] Hide left navigation column by default
• [x] Hide "Home" and "About" links and github icon in header
• [x] Add left-side hamburger menu
• [x] Tapping hamburger menu opens drawer showing "Home" and "About" links and the left nav (see mocks)
• [x] Reduce left padding/margin on main report view to 1.5 rem (1rem on the bar chart)

I can't find a great place to put the github icon on mobile so for now I think just hide it to free up space in the header; we can add it back in later.

@lightningorb this design is intended to be minimum viable from an engineering standpoint, lmk any of this seems much more difficult than some other obvious solution.

[lightningorb]

ok this is done, with the addition of the drawer going over the content on mobile. Also added a slide in and out transition, with a box shadow on mobile.

[lightningorb]

Done.