use nested @applies instead of copy pasta

[notwaldorf]

Nested applies actually work, so let's do that instead. Also, this will allow us to be able to change the font magically for all paper elements, by overriding the right mixin:

<style is="custom-style">
    :root {
      --paper-font-common-base: {
        font-family: serif !important;
      };
    };
</style>

[abdonrd]

Yeah! Since when the nested applies works?

[notwaldorf]

@abdonrd not sure, to be honest. for a while.

[cdata]

beautiful 💇 LGTM 👍