- Set flex-flow of the list to "row wrap" to make the footer adaptive.
- Set display of the list to flex to make it clear we're using it.
This is already set in Pico CSS so it isn't necessary, but I think
it's nicer to have it set again explictly.
See here for the relevant Pico CSS code:
aaa1ffe05c/scss/components/_nav.scss (L20)
If a page is not a page bundle, it can't access files in the same
directory via the .Resources variable. So we need to detect this
condition and get the image file in another way.
