Allow for non-floating footer

[jonseitz]

Describe your changes

This adds a position prop to the <Footer> component, which is passed through the the CSS property of same name to allow for customization of the Footer styling. It also changes the default from fixed to sticky, which means that it will "un-float" when the window scrolls to the end of the page content -- that should fix the issue we've sometimes seen with the footer covering up the bottom of the page.

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] I have run eslint on the code
• [x] I have added JSDoc for all of my code (where applicable)
• [ ] I have added tests to cover my changes.

Priority:

• [x] Normal
• [ ] High

Related Issues:

Fixes #161

[jonseitz]

Also, I'm curious as to how you tested this - did you have to downgrade your version of node for the time being? I can't get styleguidist server to run properly on Node 18.

Sort of? I just ran it in a node:14 docker container and was able to get it working:

docker run -it --rm -p 127.0.0.1:6060:6060 -v $(pwd):/node node:14 bash -c "cd /node; npm run start"

I did also play around with upgrading webpack, styleguidist, etc for a bit and got it to compile, but any time I tried to load the styleguide there was an error with some kind of polyfill it was trying to apply.