The pets icon is just the same as the notpet but without the diagonal
bar.
The price is hardcoded in the query for now, as there is no field
in the campsite type.
This one has an input to select the icon. It makes no sense to choose
an icon only by name, thus a <select> is not appropriate, and had to
use a hidden input with a row of button to choose the icon from. This
works now only because there are very few icons; we’ll need to choose
a different approach when there are many more icons.
Since now the icons have to be defined in CSS for both the public and
admin sections, i had to split it into a separate file that both sites
can use. I considered the option to “include” that CSS with m4, like
i do for images in demo.sql, but it made everything too complicated
(e.g., having to call make for each change in the CSS), and decided to
load that CSS in a separate <link>.