Weird white stripes on Firefox Android
On Brave-Android it works as expected. On Firefox-Android however, it does not work at all. There are two white stripes on the site. One under the iframe that holds the header and the other at the very bottom of the site.
I have added two screenshots to this question. One screenshot shows how it is supposed to look, the other one shows the problem I am facing.
If you want to check out the code, I did upload everything to GitHub. The site itself is in German, but all the variable are in English.