Padding issue and icon missing in success message in calendar invitation

Related issue: https://gitlab.e.foundation/e/infra/backlog/-/issues/1020

Steps to reproduce

Accept an invitation on a mobile device like a FP4

What is the current behavior?

Several issue for the succesful page:

• right border is truncated
• an horizontal scroll bar is displayed
• the footer should be on the bottom of the page

What is the expected correct behavior?

Beautiful page.