### Steps to reproduce

1. Use the Gantt view

2. Select a work package and open the split view (the (i) icon)

3. Go to relations tab, and create a child from the drop down menu


### What is the buggy behavior?

* The view height is reduced to an unusable height

* The split view width is expanded and cannot be reduced


### What is the expected behavior?

1. Child added normally


### Screenshots and other files

Please see the attached screen capture video.

After creating the child, it looks like this:

<img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/264105/content">

### Begin of the insertionNote

this also happens from the Team planner and the Calendar module
<img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/267250/content">

### <img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/267252/content">

###End of the insertion Environment information

**OpenProject installation type**

* Hosted cloud edition

* edge environment


**OpenProject version**

Core build: [0080542c742ebc40fbd21a1efaa1612d82fefa3b](https://github.com/opf/openproject/commits/0080542c742ebc40fbd21a1efaa1612d82fefa3b)

Product version: [d460de4c2660987bb163452ee93daa55cc758daf](https://github.com/opf/saas-openproject/commits/d460de4c2660987bb163452ee93daa55cc758daf)

Core version: OpenProject 15.3.0

**Browser**

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