Theme improvements

[XhmikosR]

Some things I noticed while playing around with the repo

1. I'm not sure if we really use Font Awesome; if not we should find a way to disable it - EDIT: it seems it's included for the social icons which is an overkill IMO, but an upstream issue, see squidfunk/mkdocs-material#1364
2. We should inline or at least combine extra CSS and material CSS which imports the fonts - EDIT upstream issue
3. IMHO the main text font-size (14px) is too small; we should use the default .8rem
4. Might be worth either preconnecting or at least DNS prefetching api.github.com - EDIT upstream issue but we could just add the template partial and modify it

Some of these issues (1, 4) we might need to report upstream for everyone to benefit

[XhmikosR]

I think the only thing we can tackle is the third point.

From playing around I found these quite good, but still smaller than the upstream sizes:

.md-nav {
    font-size: .65rem;
    line-height: 1.4;
}

.md-typeset {
    font-size: .7rem;
    line-height: 1.5;
}