New pattern pat-sticky

[pilz]

Cornelis found this:

https://github.com/wilddeer/stickyfill which behaves great in Chrome and IE and Edge. Would love to have this one as pat-sticky but there’s only one thing it doesn’t do that would be nice and that’s a class ‘stuck’ or similar when it’s touching the edge. Sometimes you want a bumper, sometimes a sticky, but sticky — which is CSS native — is not supported yet in Blink. Safari and FF do it perfectly, so this polyfill comes at hand