Create activity modal is not fully visible at activities page

[MahtabBukhari]

Describe the bug
When we go to the activites page and select activity and then click on Reply button the the Create Activity Modal open that is hidden and not clearly visible and also there is not close icon on the modal

To Reproduce
Steps to reproduce the behavior:

1. Go to 'activities page'
2. Click on 'one activity and then click on Rely button'
3. Modal is opened
4. You can then see bug

Expected behavior
https://www.loom.com/share/4283474bd9ac44db825d4cbf590cec70?sid=1383be5f-cc8d-4549-b4ff-02f3bbc76f0a

Acceptance Criteria

• I have tested on Chrome desktop
• I have posted a screenshot or video in my PR
• I have rebased and tested locally before submitting my PR
• I can submit a PR within 2 days of taking the bounty

[MahtabBukhari]

@tomsmith8 @Edvardoh @Evanfeenstra Could you review the issue and assign to me?