Button colours and labels are confusing when changing submission state

[MacLemon]

Steps to Reproduce:

1. create a submission in error
2. delete that submission again to cover up your tracks
3. get confused by the confirmation dialogue's buttons.

Expected Results:

The back button should not exist as a back button. Why replicate a browser button that's always there in the chrome. A button that would make sense, even if only to provide a button for the panicking user, would be a “Cancel” button. It should be green or white. This action is non-destructive.

The “Do it” button is a destructive action. It should be red to indicate this.

Actual Results:

The Back button is a non-destructive action, it should not be crimson coloured.
The “Do it” button is green, though it is a destructive action.

Regression:

n/a

Notes:

Provide additional information, such as references to related problems, workarounds and relevant attachments.

Version Information:

Chromium 68.0.3429.0 (Official Build) (64-bit)
pretalx 0.6.1

[MacLemon]

In addition to this, the above colour problem only applies in certain circumstances depending on from which to which other state you want to change the submission. @luto and I are matrix thinking about how to improve that non trivial problem.