Improve user experience on mobile

Is your feature request related to a problem? Please describe.
While it's possible to toggle the relevant dialog for the interaction buttons, to show the map, would it be possible to optimize their layout further to improve the contributors' experience on mobile devices? (Sorry, I'm not sure if using the proper terms.)

Describe the solution you'd like
Currently, we have this toolbar at the bottom of the page on mobile browsers:

The toolbar, and the dialog/interaction takes up more than half of my phone screen, tho you can toggle the dialog. Maybe three states are possible, with a more compact toolbar/dialog that allow users to see more of the map and the feature they're trying to fix/review?

Also, the transition from task completion to the next task dialog, this dialog box feels visually jarring and inconsistent, which gives the app a sense of incompleteness. :

Additional context
The MapRoulette platform performs quite well on the desktop, but maybe we're missing an opportunity to make it more convenient/inviting by improving the user-experience of people who are keen to improve OpenStreetMap, but are on mobile devices.

Start by reproducing the toolbar, interaction dialog, and task-completion transition on a mobile browser, comparing them with the screenshots in the issue. Done means the mobile layout offers more compact states, preserves map visibility, and makes the transition between tasks visually consistent.