How affix (sticky) works (bootstrap 4)?

[berpcor]

https://jsfiddle.net/1u6o412b/
As you can see everything is working (test in xs size), but try to delete styles for .h and .t, and you'll see that header is behind the content. Why is this happening? It is higher in DOM than content. Is it normal to use z-index for such goal?

[mdo]

Issues are for bug reports and feature requests, not general how-to questions. For that, we suggest the official Slack channel or Stack Overflow. Both are linked from our readme.

Thanks!