[Clock/Calendar] Always show current date

[donovanglover]

Is your feature request related to a problem? Please describe. It would be nice if there was a way to always highlight the current date. Currently if you click another date the current date doesn't have any sort of indicator.

Describe the solution you'd like Ability to style dates with CSS. Might already be possible? https://docs.gtk.org/gtk4/class.Calendar.html#css-nodes

Describe alternatives you've considered Could make clicking on the header select the current year/month/day. Would be useful when looking at dates from a few months before.

Could also select the current date again when the calendar popup is opened/closed instead of persisting state.