Documentation footer issues

[Luyao Yang]

There are a few issues with the footer in our documentations:

Footer should be anchored to the bottom

We have a good number of pages on our docs that have short content, for example this page. On my 1920x1080 screen it looks like this:

We should add a global style that ensures the content at least fills one screen so that the footer is pushed down to always appear at the bottom of the screen. maybe something like this:

main {
  min-height: calc(100vh - 72px);
}

Footer is hard to read

The colors on the footer make it hard to read. We should change the colors (probably make it less bright too). Would also be nice if all the blues on our docs were the same shade.

Footer is wrong

It is built with sphinx, but the rest isn't true...