A few, probably fixable HTML validation errors

Hey!

Thanks for sharing a cool plugin with the community.

I am wondering – is there a chance that the minor HTML validation errors could be fixed? They seem rather trivial, and having a site that passes HTML validation is important to some..

Screenshot: https://snipboard.io/hmOsw1.jpg

For more info on the errors encountered: https://validator.w3.org/nu/?doc=https%3A%2F%2Foldrup.net%2Fstackable%2F

Kind regards
Bjarne

The page I need help with: [log in to see the link]