Background changing size in beetwen pages

❌ Description of the bug

The background image changes size when moving between home and forums page

✔ Expected Behaviour

I expect it to not change size

✨ How do you reproduce this bug?

I have no clue

🌳 Website Environment

• PHP Version: [e.g. 7.4]
• Database driver (please include the version aswell): [e.g. MySQL 5.8, MariaDB 10.6]
• Application Version: [e.g. 1.2.5]

📋 Additional Information

images for context