fix: [BB-4143] Reused style in registration

[farhaanbukhsh]

Reused the style for background image

JIRA tickets: BB-4143

Discussions: PR

Dependencies: None

Screenshots:

Sandbox URL: TBD - sandbox is being provisioned.

Merge deadline: "None" if there's no rush, "ASAP" if it's critical, or provide a specific date if there is one.

Testing instructions:

1. Get the devstack running
2. Check http://localhost:3000/registration/domain
3. Check the congratulation page as well

Author notes and concerns:

1. Instead of using the same class I went with mixin approach

Reviewers

• @0x29a

[0x29a]

👍

• I tested that background is present on registration pages.
• I read through the code.