Refactor auth form styles

Closes #4246

- Removed the input wrapper background colour
- Moved `:focus` styles to one element, so its not defined separate for each page
- Removed unnecessary MQ for body background colour (it changed nothing)
Merge pull request #4249 from PaulAdamDavis/fix-signin-styles

Refactor auth form styles
Change keyboard shortcut context

closes #4247
- added scope to every shortcut, the scope of shortcut is default to
  'default'
- add shortcut `enter` to modal which confirm the modal
- shortcut `enter` and `esc` now have scope 'modal'
- when lunch a modal, scope is switching to 'modal', and set back to
  'default' when close
- shortcut `enter` now confirm the dialog without conflicting with route
  shortcuts
Merge pull request #4265 from RaoHai/issue-4247

Change keyboard shortcut context