Why my navigation is not floating?

[FrankMe]

Hallo,

i did a bootstrap site like the example here:
https://www.w3schools.com/bootstrap4...spy2&stacked=h

But on my page the navigation is not floating on the left site. wehlen.mehlhop.com Insteat it is fixet on the top left.
What I need to change to get the navigation floating so it is allways visible on the left?


Frank

[FrankMe]

I did not make changes, but after view hours it works as it should.