fix(avatar): prevent avatar from obscuring name

Increase z-index of avatar-name so that avatar image doesn’t obscure it
when riding a mount
fix(tasks): improve UI consistency and layout

* Match UI elements with rest of site
* Tidy up layout
Closes #4361
Merge branch 'develop' of github.com:HabitRPG/habitrpg into develop
Changing button to a element fixed the delete on enter problem