Reset `-webkit-font-smoothing`

[nanxstats]

In the default Bootswatch theme "cosmo" that Quarto book uses, there is this rule:

body {
  -webkit-font-smoothing: antialiased;
}

This rule might not be too useful in web typography today (search "stop fixing font smoothing" and see the opinions).

So I would propose to reset it to:

body { 
  -webkit-font-smoothing: auto; 
}

I will send a PR.