Pressing Back from Campaign preview shows edit page in pink.

[quintrino]

Describe the bug

1. viewing a campaign
   https://ruby.org.au/admin/campaigns/219/edit
2. selecting preview
   and then
3. pressing back shows the page in a full pink.

Applies to both historical campaigns and active campaigns.
Applies in Chromium based browsers and Firefox based browsers.

Expected behavior

It should load the regular page as before.

Screenshots

Desktop (please complete the following information):

• OS version: macOS 26.5.1
• Architecture: x86_64

Add any other context about the problem here.

[leesheppard]

I think the Preview link should open in a new window/tab rather than the same window and forcing the user to hit the Back button.