Metric-compatible font with Times New Roman created by ParaType, based on
their serif font PT Serif, released under OFL-1.1 license.
https://www.paratype.com/fonts/pt/pt-astra-serif
Signed-off-by: Coelacanthus <uwu@coelacanthus.name>
and try to load the font family (guessed from the font name) before trying
the local substitution.
The local(...) command expects to have a real font name and not a predefined
substitution it's why we try the font family.
Given that the `css` property isn't constant, since it contains document/font ids, we cannot just check it directly. However, we can make use of regular expressions to ensure that the format is generally correct.
