### Steps to reproduce

1. Login as a user with admin permissions

2. Go to Projects > Project life cycle > Edit phase

3. Check the Details and Phase gates tabs


### What is the buggy behaviour?

* The navigation tab doesn't belong to the content of the screen is an option of the [PageHeader component](https://qa.openproject-edge.com/lookbook/pages/components/page_header)

* The spacing between elements in the form of the phases gates tab doesn't follow the designs of 1rem of space between form elements


### What is the expected behaviour?

* Begin of the insertion~~PleaseEnd of the insertion Begin of the deletion PleaseEnd of the deletion use the component created for this and fully documented in Begin of the insertionthe~~ [~~LookbookEnd of the insertion Begin of the deletion the [LookbookEnd of the deletion for Begin of the insertionPageHeader~~](https://qa.openproject-edge.com/lookbook/inspect/primer/open_project/page_header/tab_nav)~~.~~End of the insertion Begin of the deletion PageHeader](https://qa.openproject-edge.com/lookbook/inspect/primer/open_project/page_header/tab_nav).End of the deletion

* Begin of the insertion~~ThisEnd of the insertion Begin of the deletion ThisEnd of the deletion will remove the double divider Begin of the insertionproblem~~End of the insertion Begin of the deletion problemEnd of the deletion

* Begin of the insertion~~TheEnd of the insertion Begin of the deletion TheEnd of the deletion tab nav will then go full width as Begin of the insertiondesigned~~End of the insertion Begin of the deletion designedEnd of the deletion

Begin of the insertion* Remove tab panels and join their content (we will reconsider if and when forms get more complicated)

End of the insertion * Add the proper spacing (1rem) in the form of phase gates


### Screenshots and other files

<img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/668629/content"><img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/668630/content">

### Environment information

**OpenProject version**

QA Edge

**Browser**

* [x] Chrome
* [x] Firefox
* [x] Safari
* [ ] Mobile Safari
* [ ] Other (please specify)

**Operating System**

* [ ] Windows
* [x] Mac OS X
* [ ] Mobile iOS
* [ ] Mobile Android
* [ ] Linux (please specify distro)
* [ ] Chrome OS
* [ ] Other (please specify)

**Language**

_All_