Anyone?
Anyone?
Thank you Sergiy! I found a useful JS library to work with.
For anyone in need of this: I'm gonna write out the code and post it here afterwords.
Following advice from another thread, the problem has been solved.
My browser cache had to be cleared.
The problem is fixed now but it's still very weird that something like this can occur. Maybe an idea for the engineers of appery to look into this?