Mobile / responsive interface

Hey,
currently it seems that Oncall is not ready for mobile browsers

![Image](https://github.com/user-attachments/assets/ee1c7ba4-22cd-4be5-824f-72209c6f7a5a)

![Image](https://github.com/user-attachments/assets/8fc2e4c0-19ed-4dad-b2f5-f159b9997f24)

![Image](https://github.com/user-attachments/assets/aca169b1-6e4a-40fb-b4d8-4ffba9afb95d)